Pyrazolopyridine and pyrazolopyrimidine derivatives as melanocortin-4 receptor modulators

ABSTRACT

Disclosed herein is a compound of Formula I: wherein X, R 1 , R 2 , and R 3  are as defend herein, or a pharmaceutically acceptable salt thereof to allow the drug to penetrate the cell membrane; or a prodrug, or the compound is labeled with a detectable label or an affinity tag thereof. Also disclosed is a pharmaceutical composition, a method of treating a disorder mediated by melanocortin-4 receptors, and a method of treating obesity using the compounds described.

This application is a 35 U.S.C. §371 national phase application ofPCT/CA2012/000089, filed Jan. 26, 2012, which claims benefit of U.S.Provisional Patent Application No. 61/436,727, filed Jan. 27, 2011, theentire contents of which are incorporated herein by reference as iffully set forth.

TECHNICAL FIELD

The present concerns pyrazolopyridine and pyrazolopyrimidinederivatives, their compositions and method of using same to modulate theactivity of melanocortin-4 receptors.

BACKGROUND

Obesity represents the most prevalent of body weight disorders, and itis the most important nutritional disorder in the Western world, withestimates of its prevalence ranging from 30% to 50% of the middle-agedpopulation. The number of overweight and obese Americans has continuedto increase since 1960, a trend that is not slowing down. Today, 64.5percent of adult Americans (about 127 million) are categorized as beingoverweight or obese. Each year, obesity causes at least 300,000 deathsin the U.S., and healthcare costs of American adults with obesity amountto approximately $100 billion (American Obesity Association).

Obesity increases an individual's risk of developing conditions such ashigh blood pressure, diabetes (type 2), hyperlipidemia, heart disease,hypertension, stroke, gallbladder disease, and cancer of the breast,prostate, and colon (see, e.g., Nishina, P. M. et al, Metab. 1994, 43,554; Grundy, S. M. & Barnett, J. P., Dis. Mon. 1990, 36, 641). In theU.S., the incidence of being overweight or obese occurs at higher ratesin racial/ethnic minority populations such as African American andHispanic Americans, compared with Caucasian Americans. Women and personsof low socioeconomic status within minority populations appear toparticularly be affected by excess weight and obesity. This trend is notlimited to adults. Approximately 30.3 percent of children (ages 6 to 11)are overweight and 15.3 percent are obese. For adolescents (ages 12 to19), 30.4 percent are overweight and 15.5 percent are obese. Diabetes,hypertension and other obesity-related chronic diseases that areprevalent among adults have now become more common in children and youngadults. Poor dietary habits and inactivity are reported to contribute tothe increase of obesity in youth. Additionally, risk factors fordeveloping childhood obesity include having overweight parents, orparents unconcerned about their child's weight, increased energy intakedue to larger serving sizes, increased sedentary lifestyle and decreasedtransport-related activity (walking to school or to the bus stop),having a temperament with high levels of anger/frustration (which maycause parents to give their child extra food and calories to decreasetantrums), having Down's Syndrome, mother's pregnancy body mass index(BMI) and first born status (increased prevalence of obesity). One toolused for diagnosing obesity in adults is calculating an individual'sBMI, which is a measure of body weight for height (Garrow & Webster,International Journal of Obesity 1985, 9, 147). A BMI of 25 to 29.9indicates that an individual is overweight, while a BMI of 30 or aboveis indicative of obesity. For children, BMI is gender and age specific(Pietrobelli et al, Journal of Pediatrics 1998, 132, 204). Risk factorsfor developing obesity in adulthood include poor diet (high-calorie, lownutrients); lack of physical activity; working varied shifts; quittingsmoking, having certain medical conditions such as rare hereditarydiseases, and hormonal imbalances (such as hypothyroid, Cushing'sdisease and polycystic ovarian syndrome); certain medications (steroidsand some antidepressants); being a racial or ethnic minority (especiallya female minority); low socioeconomic status; age (increased risk from20-55), pregnancy; and retirement (due to altered schedule).

Melanocortin 4 Receptor and Obesity

Melanocortin (MC) receptors are members of theseven-transmembrane-domain G protein-coupled receptor superfamily thatactivate generation of the second messenger cyclic AMP (cAMP). There arefive MC receptors isolated to date: MC1R, MC2R, MC3R, MC4R and MC5R.Human MC4R is 332 amino acids in length. The melanocortin 4 receptor(MC4R) has been implicated in the regulation of body weight (Graham etal, Nat. Genetics 1997, 17, 273). MC4R is expressed in the brain,including the hypothalamus, which influences food intake (Markison &Foster, Drug Discovery Today, 2006, 3, 569).

Signaling via MC4R stimulates anorexigenic neural pathways. MC4R nullmice develop late onset obesity with hyperglycemia and hyperinsulinemia.Mice lacking one MC4R allele (heterozygotes) have intermediate bodyweight between wild-type and homozygous null mice. Transgenic miceoverexpressing an endogenous MC4R antagonist, i.e. agouti-relatedprotein (AgRP), exhibited increased weight gain, food consumption, andbody length compared with non-transgenic littermates (Oilman et al.,Science 1997, 278 135). In humans, MC4R deficiency is the most commonmonogenic form of obesity (Farooqi et al., New Engl. J. Med. 2003 348,1085). Numerous mutations affecting MC4R activity have been found andmany are associated with obesity including early-onset (childhood)obesity (Nijenhuis et al., J. Biol. Chem. 2003, 278, 22939; Branson etal., New Eng. J. Med. 2003, 348, 1096; Gu et al., Diabetes 1999, 48,635; Tao et al., Endocrinology 2003, 144, 4544). Recently,pharmacological restoration of mutant melanocortin-4 receptor signalingwith cell permeable MC4R ligands has also been reported (René et al. J.Pharmacol. Exp Ther. 2010, 335, 520).

Several authors have now reviewed the recent advances in ourunderstanding of the genetics of MC4R in early onset obesity (e.g.,Farooqi I S & O'Rahilly S, Int J Obes (Lond), 2005 October, 29(10),1149; Govaerts et al., Peptides, 2005 October, 26(10), 1909; Tao Y X,Mol Cell Endocrinol, 2005 M 15, 239(1-2), 1-14; Farooqi I S & O'RahillyS, Annu Rev Med, 2005, 56, 443-58). For example, in one patient withsevere early-onset obesity, an autosomal-dominant mode of inheritance ofan MC4R mutation has been found to be due to a dominant-negative effectcaused by receptor dimerization (Biebermann H et al. Diabetes, 2003December, 52(12), 2984).

Natural agonists (ligands) of MC4R include [alpha]-MSH, ACTH,[beta]-MSH, and [gamma]-MSH (in order from highest to lowest affinity).Other MC4R ligands, including agonists and antagonists, which have beendescribed to date are peptides (U.S. Pat. No. 6,060,589) and cyclicpeptide analogs (U.S. Pat. No. 6,613,874 to Mazur et al.). Further, U.S.Pat. Nos. 6,054,556 and 5,731,408 describe families of agonists andantagonists for MC4R that are lactam heptapeptides having a cyclicstructure. A series of MC4R peptide agonists have also been designed(Sun et al., Bioorg Med Chem 2004, 12(10):2671). In addition, Nijenhuiset al. (Peptides 2003, 24(2):271) described the development andevaluation of melanocortin antagonist compounds that were selective forthe MC4R. One compound, designatedAc-Nle-Gly-Lys-D-Phe-Arg-Trp-Gly-NH(2) (SEQ ID NO:9), was found to bethe most selective MC4R compound, with a 90- and 110-fold selectivityfor the MC4R as compared to the MC3R and MC5R, respectively. Subsequentmodification yielded compound Ac-Nle-Gly-Lys-D-Nal(2)-Arg-Trp-Gly-NH(2)(SEQ ID NO: 10), a selective MC4R antagonist with 34-fold MC4R/MC3R and109-fold MC4R/MC5R selectivity. Both compounds were active in vivo, andcrossed the blood-brain barrier. On the other hand, it was recentlyshown that the moderately selective peptide antagonist PG-932 (7-foldMC4R/MC3R selectivity) increased food intake in mice upon peripheraladministration (Sutton et al. Peptides, 2008, 29, 104). A recent reportalso describes the activation of mutated MC4R by novel peptide agonists(Roubert et al., J. of Endocrinology, 2010, 207, 177).

Other high-affinity MC4R antagonists are described in Grieco et al. (JMed Chem 2002; 24:5287). These cyclic antagonists were designed based onthe known high affinity antagonist SHU9119(Ac-Nle4-[Asp5-His6-DNal(2′)7-Arg8-Trp9-LyslO]-NH(2)) (SEQ ID NO: 11).The SHU9119 analogues were modified in position 6 (His) withnon-conventional amino acids. One compound containing a Che substitutionat position 6 is a high affinity MC4R antagonist (IC50=0.48 nM) with100-fold selectivity over MC3R. Another compound with a Cpe substitutionat position 6 also was a high affinity MC4R antagonist (IC50=0.51 nM)with a 200-fold selectivity over MC3R. Molecular modeling was used toexamine the conformational properties of the cyclic peptides modified inposition 6 with conformationally restricted amino acids. See also,Grieco et al., Peptides 2006, 27, 472. Several non-peptide MC4R ligandshave also been disclosed in U.S. published patent applications2003/0158209 to Dyck et al. and 2004/082590 to Briner et al. Also, U.S.Pat. No. 6,638,927 to Renhowe et al. describes small, low-molecularweight guanidobenzamides as specific MC4R agonists. Richardson et al.,have described novel arylpiperizines that are agonists of MC4R (J MedChem 2004; 47(3), 744). U.S. Pat. No. 6,979,691 to Yu et al. and U.S.Pat. No. 6,699,873 to Maguire also describe non-peptide compounds whichbind selectively to MC4R. WO 99/55679 to Basu et al. disclosesisoquinoline derivatives, small molecule non-peptide compounds, whichshow low (micromolar) affinities for the MC1R and MC4R, reduction ofdermal inflammation induced by arachidonic acids, and reductions of bodyweight and food intake. WO 99/64002 to Nargund et al. also disclosesspiropiperidine derivatives as melanocortin receptor agonists, usefulfor the treatment of diseases and disorders such as obesity, diabetes,and sexual dysfunction. A large number of MC4-receptor ligands developedrecently are analogs of N-acylpiperidines or piperazines (Nozawa et al.Expert Opin. Ther. Patents, 2008, 18, 403).

Other non-peptide MC4R antagonists have been described. Thus, U.S.published patent applications 2003/0176425 and 2003/0162819 to Eisingeret al. disclose novel 1,2,4-thiadiazole and 1,2,4-thiadiazoliumderivatives, respectively, as MC4R antagonists or agonists. Theseapplications also disclose use of these compounds to treat obesity.Other MC4R binding compounds are described in the following: Singh etal. J. Med. Chem., 2011, 54, 1379; Mayorov et al., Bioorg. Med. Chem.Lett., 2011, 21, 3099; Conde-Frieboes et al., Bioorg. Med. Chem. Lett.,2011, 21, 1459; Hong et al., Bioorg. Med. Chem. Lett., 2011, 21, 3099;DeBoer, Nutrition, 2010, 26, 146. He et al. Bioorg. Med. Chem. Lett.2010, 20, 6524. Emmerson et al., Curr. Top. Med. Chem. 2007, 7, 1121.Nargund et. al. J. Med. Chem. 2006, 49, 4035. Guo et al., Bioorg. Med.Chem. Lett. 2008, 18, 3242. Sebhat et al. Bioorg. Med. Chem. Lett. 2007,17, 5720. Chen et al. Bioorg. Med. Chem. 2008, 16, 5606. Marinkovic etal. Bioorg. Med. Chem. Lett. 2008, 18, 4817. Tran et al., Bioorg. Med.Chem. Lett. 2008, 18, 1124. Tran et al. Bioorg. Med. Chem. Lett. 2008,18, 1931. Bednarek & Fong, Exp Opn Ther Patents 2004, 14, 327;Ujjainwalla et al., Bioorg. Med. Chem. Lett. 2005, 15, 4023;WO11/054,285 (Zhang Ga); WO 10/144,344 (Palatin); WO 10/065,801(Palatin); WO 10/037,081 (Palatin); WO 10/065,802 (Palatin); WO10/065,801 (Palatin); WO 10/065,800 (Palatin); WO 10/065,799 (Palatin);WO 03/07949 (Merck); WO 10/081,666 (Santhera); WO 10/034,500 (Santhera);WO 09/080291 (Santhera); WO 09/115321 (Santhera); WO 04/075823 (Ipsen);WO 04/089951 (Ipsen); WO 05/056533 (Ipsen); WO 06/010811 (Ipsen); WO03/61660 (Eli Lilly); WO 03/09847 (Amgen); WO 03/09850 (Amgen); WO03/31410 (Neurocrine Biosciences); WO 03/94918 (Neurocrine Biosciences);WO 03/68738 (Neurocrine Biosciences); WO 03/92690 (Procter and Gamble);WO 03/93234 (Procter and Gamble); WO 03/72056 (Chiron); WO 03/66597(Chiron); WO 03/66587 (Chiron); WO 03/66587 (Chiron); WO 02/67869(Merck); WO 02/68387 (Merck); WO 02/00259 (Taisho); WO 02/92566(Taisho); WO 02/070511 (Bristol-Myers Squibb); WO 02/079146(Bristol-Myers Squibb); WO 10/056,022 (LG Life Sciences); Pontillo etal., Bioorg Med Chem. Lett. 2005, 15, 5237; Pontillo et al., Bioorg MedChem. Lett. 2005, 15, 2541; Pontillo et al., Bioorg Med Chem. Lett.2004, 14, 5605; Cheung et al., Bioorg Med Chem. Lett. 2005, 15, 5504;Yan et al., Bioorg Med Chem. Lett. 2004 15, 4611; Hsiung et al.,Endocrinology. 2005, 146, 5257; and Todorovic et al., Peptides. 2005October, 26(10), 2026.

Current Treatments

Current anti-obesity drugs have limited efficacy (Jones, Nat. Rev. DrugDiscov. 2009, 8, 834. Yao & Mackenzie, Pharmaceuticals, 2010, 3, 3494)and numerous side effects (Crowley et al., Nat. Rev. Drug Discov. 2002;1, 276). With obesity reaching epidemic proportions worldwide, there isa pressing need for the development of adequate therapeutics in thisarea. In recent years, hormones and neuropeptides involved in theregulation of appetite, body energy expenditure, and fat massaccumulation have emerged as potential anti-obesity drugs (McMinn, etal., Obes Rev 2000, 1, 37; Drazen, D. L. & Woods, S. C, Curr Opin ClinNutr Metab Care 2003, 6, 621). At present, however, these peptidesrequire parenteral administration. The prospect of daily injections tocontrol obesity for extended periods of time (since obesity is a chroniccondition) is not very encouraging and limits the use of these drugs.

Thus, there is a need for improved pharmacological agents that areuseful to treat obesity in humans.

BRIEF SUMMARY

Accordingly, there is provided a compound of Formula I:

whereinX═CH, or N;R¹ is

-   -   1) halogen,    -   2) C₁-C₆ alkyl,    -   3) C₃-C₇ cycloalkyl,    -   4) aryl,    -   5) heteroaryl,    -   6) NHR⁴,    -   7) C(O)NHR⁴,    -   8) C(O)-aryl,    -   9) C(O)-heteroaryl, or    -   10) C(O) heterocyclyl,        wherein the aryl and the heteroaryl are optionally substituted        with one or more R⁷ substituents;        R² is    -   1) C₁-C₆ alkyl-heterocyclyl,    -   2) C₁-C₆ alkyl-NR⁵R⁶,    -   3) C₃-C₆ alkenyl-heterocyclyl,    -   4) C₃-C₆ alkenyl-NR⁵R⁶,    -   5) C₃-C₆ alkynyl-heterocyclyl,    -   6) C₃-C₆ alkynyl-NR⁵R⁶,    -   7) aryl C₁-C₃ alkyl-heterocyclyl, or    -   8) C(O)NH C₂-C₆ alkyl-heterocyclyl,        wherein the heterocyclyl is optionally substituted with one or        more C₁-C₆ alkyl substituents, or one or more halo substituents,        or one or more haloalkyl substituents;        R³ is    -   1) NR⁸R⁹,    -   2) C(O)NR⁸R⁹,    -   3) C(═NH)NR⁸R⁹,    -   4) C(═NC₁-C₆ alkyl)NR⁸R⁹,    -   5) C(S)NR⁸R⁹,    -   6) CH₂NR⁸R⁹, or    -   7) C(O)heterocyclyl optionally substituted with a C₁-C₆ alkyl        substituent;        R⁴ is    -   1) aryl,    -   2) heteroaryl,    -   3) C₁-C₆ alkyl-aryl,    -   4) C₁-C₆ alkyl-heteroaryl,    -   5) C₁-C₆ alkyl-NHC(O)C₁-C₆ alkyl,    -   6) C₁-C₆ alkyl-O—C₁-C₆ alkyl, or    -   7) C₁-C₆ alkyl-heterocyclyl,        wherein the aryl, the heteroaryl and the heterocyclyl are        optionally substituted with one or more R⁷ substituents;        R⁵ and R⁶ are both or each independently,    -   1) H,    -   2) C₁-C₆ alkyl,    -   3) C₁-C₆ alkyl-aryl, or    -   4) heterocyclyl;        R⁷ is    -   1) CN,    -   2) halogen,    -   3) haloalkyl,    -   4) C₁-C₆ alkyl,    -   5) OC₁-C₆ alkyl,    -   6) O-aryl,    -   7) O—C₁-C₆alkyl-aryl,    -   8) C(O)OC₁-C₆ alkyl,    -   9) C(O) C₁-C₆ alkyl,    -   10) C(O) aryl,    -   11) C(O) heteroaryl,    -   12) C(O)NH C₁-C₆ alkyl,    -   13) NHC(O) C₁-C₆ alkyl,    -   14) C(O)OH,    -   15) C(O)NH₂,    -   16) NO₂,    -   17) heterocyclyl,    -   18) C₁-C₆ alkyl heterocyclyl,    -   19) heteroaryl,    -   20) aryl,    -   21) NH₂    -   22) OH,    -   23) CH(OH) C₁-C₆ alkyl,    -   24) C(OH)(C₁-C₆ alkyl)₂,    -   25) C(NH₂)═NH,    -   26) C(NH₂)═N—OH, or    -   27) C(NH₂)═N—OC(O) C₁-C₆ alkyl,        wherein the heteroaryl is optionally substituted with aryl,        C₁-C₆ alkyl, haloalkyl, heteroaryll or CH₂-aryl-F; and        R⁸ and R⁹ are both or each independently    -   1) C₃-C₇-alkyl, or    -   2) C₁-C₄-alkyl-C₃-C₆-cycloalkyl,        or a pharmaceutically acceptable salt thereof to allow the drug        to penetrate the cell membrane; or a prodrug, or the compound is        labeled with a detectable label or an affinity tag thereof.

According to another aspect, there is provided a pharmaceuticalcomposition comprising a compound of Formula I as described above and apharmaceutically acceptable carrier.

According to another aspect, there is provided a method of making apharmaceutical composition comprising mixing a compound of Formula Iwith a pharmaceutically acceptable carrier.

According to another aspect, there is provided a method of treating adisorder mediated by melanocortin-4 receptors, the method comprisingadministering to a subject in need thereof a therapeutically effectiveamount of a compound of Formula I so as to treat the disorder.

According to another aspect, there is provided a method of treatingobesity in a subject, the method comprising: administering to thesubject in need thereof, a pharmaceutically acceptable amount of acompound of Formula I, as described above, so as to treat the obesity.

According to another aspect, there is provided a method of modulatingmelanocortin-4 receptor activity, the method comprising: contacting thereceptor with a compound of Formula I in an amount sufficient tomodulate the receptor activity.

According to another aspect, there is provided an in vitro method ofmodulating melanocortin-4 receptor activity, the method comprising:contacting a cell with a compound of Formula I, as described above, inan amount sufficient to modulate the receptor activity.

According to one aspect, there is provided use of a compound, asdescribed above, to treat a disorder mediated by melanocortin-4receptors.

According to another aspect, there is provided use of a compound, asdescribed above, to treat obesity.

According to another aspect, there is provided a method of screening fora compound's ability to modulate the stability, activity, and/or cellsurface localization of an MC4R polypeptide, the method comprising:

-   -   contacting a labeled or unlabeled test compound with a MC4R        protein or a fragment thereof; and    -   measuring the amount of the test compound bound to the MC4R        protein or to the fragment.

According to another aspect, there is provided a method determiningwhether a test compound modulates the stability of the MC4R polypeptide,the method comprising:

-   -   contacting a first cell with a test compound for a time        sufficient to allow the cell to respond to the contact with the        test compound;    -   measuring the conformational stability, activity, and/or cell        surface localization of a MC4R polypeptide or a fragment        thereof; and    -   comparing the stability, activity, and/or cell surface        localization of the MC4R polypeptide measured to that of an MC4R        polypeptide in a control cell that has not been contacted with        the test compound; wherein a detectable change in the stability,        activity, and/or cell surface localization of the MC4R        polypeptide in the first cell in response to contact with the        test compound compared to the stability level of the MC4R        polypeptide in the control cell that has not been contacted with        the test compound, indicates that the test compound modulates        the stability of the MC4R polypeptide.

DETAILED DESCRIPTION 1) General Overview

We have discovered pyrazolopyridine and pyrazolopyrimidine derivativesthat have beneficial pharmaceutical properties and that these compoundsmay be effective to treat melanocortin-4 mediated diseases such asobesity, cachexia, eating disorders, diabetes, metabolic diseases,erectile dysfunction and/or sexual disorders.

2) Compounds

Broadly speaking, the present concerns compounds represented by FormulaI:

wherein X, R¹, R² and R³ are as defined hereinabove and hereinbelow, ora stable isotope or a prodrug or a pharmaceutically acceptable salt toallow the drug to penetrate the cell membrane; or the compound islabeled with a detectable label or an affinity tag thereof.

Further included within the scope of Formula I are compounds of FormulaIA and IB:

wherein R¹, R² and R³ are as defined hereinabove and hereinbelow; or aprodrug or a pharmaceutically acceptable salt to allow the drug topenetrate the cell membrane; or the compound is labeled with adetectable label or an affinity tag thereof.

Further included within the scope of Formula IA are compounds of FormulaIA1 through Formula IA50:

wherein G is C₂-C₄ alkyl, C₂-C₄ alkenyl, C₂-C₄ alkynyl, arylalkyl orC(O)NHalkyl, p is 0, 1 or 2; q is 0 or 1; M is CH₂, O, CF₂ orCH—C₁-C₆haloalkyl; E is NH or CONH, R⁵, R⁶, R⁷, R⁸, R⁹, alkyl, alkenyl,alkynyl, heteroaryl and aryl are as defined hereinabove and hereinbelow,or a prodrug; or a pharmaceutically acceptable salt to allow the drug topenetrate the cell membrane; or the compound is labeled with adetectable label or an affinity tag thereof.

Alternatively, included within the scope of Formula IB are compounds ofFormula IB1 through Formula IB50:

wherein G is C₂-C₄ alkyl, C₂-C₄ alkenyl, C₂-C₄ alkynyl, arylalkyl orC(O)NHalkyl, p is 0, 1 or 2; q is 0 or 1; M is CH₂, O, CF₂ orCH—C₁-C₆haloalkyl; E is NH or CONH, R⁵, R⁶, R⁷, R⁸, R⁹, alkyl, alkenyl,alkynyl, heteroaryl and aryl are as defined hereinabove and hereinbelow,or a prodrug; or a pharmaceutically acceptable salt to allow the drug topenetrate the cell membrane; or the compound is labeled with adetectable label or an affinity tag thereof.

In one subset of compounds of Formula IA1, there is provided a compoundof Formula IA1.1

wherein R⁷, R⁸, and R⁹ are as defined hereinabove and hereinbelow, or aprodrug; or a pharmaceutically acceptable salt to allow the drug topenetrate the cell membrane; or the compound is labeled with adetectable label or an affinity tag thereof.

In one subset of compounds of Formula IA1, there is provided a compoundof Formula IA1.2

wherein R⁷, R⁸, and R⁹ are as defined hereinabove and hereinbelow, or aprodrug; or a pharmaceutically acceptable salt to allow the drug topenetrate the cell membrane; or the compound is labeled with adetectable label or an affinity tag thereof.

In one subset of compounds of Formula IA1, there is provided a compoundof Formula IA1.3

wherein R⁷, R⁸, and R⁹ are as defined hereinabove and hereinbelow, or aprodrug; or a pharmaceutically acceptable salt to allow the drug topenetrate the cell membrane; or the compound is labeled with adetectable label or an affinity tag thereof.

In one subset of compounds of Formula IA1, there is provided a compoundof Formula IA1.4

wherein R⁷, R⁸, and R⁹ are as defined hereinabove and hereinbelow, or aprodrug; or a pharmaceutically acceptable salt to allow the drug topenetrate the cell membrane; or the compound is labeled with adetectable label or an affinity tag thereof.

In one subset of compounds of Formula IA1, there is provided a compoundof Formula IA1.5

wherein R⁷, R⁸, and R⁹ are as defined hereinabove and hereinbelow, or aprodrug; or a pharmaceutically acceptable salt to allow the drug topenetrate the cell membrane; or the compound is labeled with adetectable label or an affinity tag thereof.

In one subset of compounds of Formula IA1, there is provided a compoundof Formula IA1.6

wherein R⁷, R⁸, and R⁹ are as defined hereinabove and hereinbelow, or aprodrug; or a pharmaceutically acceptable salt to allow the drug topenetrate the cell membrane; or the compound is labeled with adetectable label or an affinity tag thereof.

In one subset of compounds of Formula IA1, there is provided a compoundof Formula IA1.7

wherein R⁷, R⁸, and R⁹ are as defined hereinabove and hereinbelow, or aprodrug; or a pharmaceutically acceptable salt to allow the drug topenetrate the cell membrane; or the compound is labeled with adetectable label or an affinity tag thereof.

In one subset of compounds of Formula IA1, there is provided a compoundof Formula IA1.8

wherein R⁷, R⁸, and R⁹ are as defined hereinabove and hereinbelow, or aprodrug; or a pharmaceutically acceptable salt to allow the drug topenetrate the cell membrane; or the compound is labeled with adetectable label or an affinity tag thereof.

In one subset of compounds of Formula IA2, there is provided a compoundof Formula IA2.1

wherein R⁷, R⁸, and R⁹ are as defined hereinabove and hereinbelow, or aprodrug; or a pharmaceutically acceptable salt to allow the drug topenetrate the cell membrane; or the compound is labeled with adetectable label or an affinity tag thereof.

In one subset of compounds of Formula IA2, there is provided a compoundof Formula IA2.2

wherein R⁷, R⁸, and R⁹ are as defined hereinabove and hereinbelow, or aprodrug; or a pharmaceutically acceptable salt to allow the drug topenetrate the cell membrane; or the compound is labeled with adetectable label or an affinity tag thereof.

In one subset of compounds of Formula IA2, there is provided a compoundof Formula IA2.3

wherein R⁷, R⁸, and R⁹ are as defined hereinabove and hereinbelow; or aprodrug; or a pharmaceutically acceptable salt to allow the drug topenetrate the cell membrane; or the compound is labeled with adetectable label or an affinity tag thereof.

In one subset of compounds of Formula IA2, there is provided a compoundof Formula IA2.4

wherein R⁷, R⁸, and R⁹ are as defined hereinabove and hereinbelow; or aprodrug; or a pharmaceutically acceptable salt to allow the drug topenetrate the cell membrane; or the compound is labeled with adetectable label or an affinity tag thereof.

In one subset of compounds of Formula IA2, there is provided a compoundof Formula IA2.5

wherein R⁷, R⁸, and R⁹ are as defined hereinabove and hereinbelow, or aprodrug; or a pharmaceutically acceptable salt to allow the drug topenetrate the cell membrane; or the compound is labeled with adetectable label or an affinity tag thereof.

In one subset of compounds of Formula IA3, there is provided a compoundof Formula IA3.1

wherein R⁷, R⁸, and R⁹ are as defined hereinabove and hereinbelow, or aprodrug; or a pharmaceutically acceptable salt to allow the drug topenetrate the cell membrane; or the compound is labeled with adetectable label or an affinity tag thereof.

In one subset of compounds of Formula IA3, there is provided a compoundof Formula IA3.2

wherein R⁷, R⁸, and R⁹ are as defined hereinabove and hereinbelow, or aprodrug; or a pharmaceutically acceptable salt to allow the drug topenetrate the cell membrane; or the compound is labeled with adetectable label or an affinity tag thereof.

In one subset of compounds of Formula IA3, there is provided a compoundof Formula IA3.3

wherein R⁷, R⁸, and R⁹ are as defined hereinabove and hereinbelow, or aprodrug; or a pharmaceutically acceptable salt to allow the drug topenetrate the cell membrane; or the compound is labeled with adetectable label or an affinity tag thereof.

In one subset of compounds of Formula IA3, there is provided a compoundof Formula IA3.4

wherein R⁷, R⁸, and R⁹ are as defined hereinabove and hereinbelow, or aprodrug; or a pharmaceutically acceptable salt to allow the drug topenetrate the cell membrane; or the compound is labeled with adetectable label or an affinity tag thereof.

In one subset of compounds of Formula IA3, there is provided a compoundof Formula IA3.5

wherein R⁷, R⁸, and R⁹ are as defined hereinabove and hereinbelow, or aprodrug; or a pharmaceutically acceptable salt to allow the drug topenetrate the cell membrane; or the compound is labeled with adetectable label or an affinity tag thereof.

In one subset of compounds of Formula IA5, there is provided a compoundof Formula IA5.1

wherein R⁷, R⁸, and R⁹ are as defined hereinabove and hereinbelow, or aprodrug; or a pharmaceutically acceptable salt to allow the drug topenetrate the cell membrane; or the compound is labeled with adetectable label or an affinity tag thereof.

In one subset of compounds of Formula IA7, there is provided a compoundof Formula IA7.1

wherein R⁷, R⁸, and R⁹ are as defined hereinabove and hereinbelow, or aprodrug; or a pharmaceutically acceptable salt to allow the drug topenetrate the cell membrane; or the compound is labeled with adetectable label or an affinity tag thereof.

In one subset of compounds of Formula IA9, there is provided a compoundof Formula IA9.1

In one subset of compounds of Formula IA11, there is provided a compoundof Formula IA11.1

wherein R⁷, R⁸, and R⁹ are as defined hereinabove and hereinbelow; or aprodrug; or a pharmaceutically acceptable salt to allow the drug topenetrate the cell membrane; or the compound is labeled with adetectable label or an affinity tag thereof.

In one subset of compounds of Formula IA21, there is provided a compoundof Formula IA21.1

wherein R⁷, R⁸, and R⁹ are as defined hereinabove and hereinbelow, or aprodrug; or a pharmaceutically acceptable salt to allow the drug topenetrate the cell membrane; or the compound is labeled with adetectable label or an affinity tag thereof.

In one subset of compounds of Formula IA31, there is provided a compoundof Formula IA31.1

wherein R⁷, R⁸, and R⁹ are as defined hereinabove and hereinbelow, or aprodrug; or a pharmaceutically acceptable salt to allow the drug topenetrate the cell membrane; or the compound is labeled with adetectable label or an affinity tag thereof.

In one subset of compounds of Formula IA41, there is provided a compoundof Formula IA41.1

wherein R⁷, R⁸, and R⁹ are as defined hereinabove and hereinbelow; or aprodrug; or a pharmaceutically acceptable salt to allow the drug topenetrate the cell membrane; or the compound is labeled with adetectable label or an affinity tag thereof.

In one subset of compounds of Formula IB1, there is provided a compoundof Formula IB1.1

wherein R⁷, R⁸, and R⁹ are as defined hereinabove and hereinbelow, or aprodrug; or a pharmaceutically acceptable salt to allow the drug topenetrate the cell membrane; or the compound is labeled with adetectable label or an affinity tag thereof.

In one subset of compounds of Formula IB1, there is provided a compoundof Formula IB1.2

wherein R⁷, R⁸, and R⁹ are as defined hereinabove and hereinbelow, or aprodrug; or a pharmaceutically acceptable salt to allow the drug topenetrate the cell membrane; or the compound is labeled with adetectable label or an affinity tag thereof.

In one subset of compounds of Formula IB2, there is provided a compoundof Formula IB2.1

wherein R⁷, R⁸, and R⁹ are as defined hereinabove and hereinbelow, or aprodrug; or a pharmaceutically acceptable salt to allow the drug topenetrate the cell membrane; or the compound is labeled with adetectable label or an affinity tag thereof.

In one subset of compounds of Formula IB2, there is provided a compoundof Formula IB2.2

wherein R⁷, R⁸, and R⁹ are as defined hereinabove and hereinbelow, or aprodrug; or a pharmaceutically acceptable salt to allow the drug topenetrate the cell membrane; or the compound is labeled with adetectable label or an affinity tag thereof.X:

In one subset of compounds, X is CH,

In another subset of compounds, X is N.

Any and each individual definition of X as set out herein may becombined with any and each individual definition of R¹, R² and R³ as setout herein.

R¹:

In one subset of compounds, R¹ is aryl optionally substituted with oneor more R⁷ substituents.

In one example, R¹ is phenyl substituted with one R⁷ substituent.

In another example, R¹ is phenyl substituted with two R⁷ substituents.

In another example, R¹ is phenyl substituted with three R⁷ substituents.

In another subset of compounds, R¹ is heteroaryl substituted with one R⁷substituent.

In another subset of compounds, R¹ is NH-aryl substituted with one R⁷substituent.

In another subset of compounds, R¹ is C(O)NH-aryl substituted with oneR⁷ substituent.

In another subset of compounds, R¹ is halogen.

In another subset of compounds, R¹ is C₁-C₆-alkyl.

Any and each individual definition of R¹ as set out herein may becombined with any and each individual definition of X, R² and R³ as setout herein.

R²:

In one subset of compounds, R² is C₁-C₆ alkyl-heterocyclyl, wherein theheterocyclyl is optionally substituted with one or more C₁-C₆ alkylsubstituents, or one or more halo substituents, or one or more haloalkylsubstituents.

In another subset of compounds, R² is C₃-C₆ alkenyl-heterocyclyl,wherein the heterocyclyl is optionally substituted with one or moreC₁-C₆ alkyl substituents, or one or more halo substituents, or one ormore haloalkyl substituents.

In another subset of compounds, R² is C₃-C₆ alkynyl-heterocyclyl,wherein the heterocyclyl is optionally substituted with one or moreC₁-C₆ alkyl substituents, or one or more halo substituents, or one ormore haloalkyl substituents.

In another subset of compounds, R² is aryl alkyl-heterocyclyl, whereinthe heterocyclyl is optionally substituted with one or more C₁-C₆ alkylsubstituents, or one or more halo substituents, or one or more haloalkylsubstituents.

In another subset of compounds, R² is C(O)NHC₂-C₆ alkynyl-heterocyclyl,wherein the heterocyclyl is optionally substituted with one or moreC₁-C₆ alkyl substituents, or one or more halo substituents, or one ormore haloalkyl substituents.

Any and each individual definition of R² as set out herein may becombined with any and each individual definition of X, R¹ and R³ as setout herein.

R³:

In one subset of compounds, R³ is C(O)NR⁸R⁹.

In another subset of compounds, R³ is C(═NH)NR⁸R⁹.

In another subset of compounds, R³ is C(═NMe)NR⁸R⁹.

In another subset of compounds, R³ is C(S)NR⁸R⁹.

In another subset of compounds, R³ is CH₂NR⁸R⁹.

Any and each individual definition of R³ as set out herein may becombined with any and each individual definition of X, R¹ and R² as setout herein.

R⁴:

In one subset of compounds R⁴ is aryl substituted with one R⁷substituent.

In one subset of compounds, R⁴ is aryl substituted with one O—C₁-C₆alkyl substituent.

In one subset of compounds, R⁴ is aryl substituted with one C(O)OC₁-C₆alkyl substituent.

In another example, R⁴ is aryl substituted with one C(O)NH₂ substituent.

In another example, R⁴ is aryl substituted with one C(O)OH substituent.

Any and each individual definition of R⁴ as set out herein may becombined with any and each individual definition of X, R¹ and R² as setout herein.

R⁵ and R⁶:

In one subset of compounds, R⁵ and R⁶ are both hydrogen.

In another subset of compounds, R⁵ is hydrogen and R⁶ is C₁-C₆ alkyl.

In another subset of compounds, R⁵ is hydrogen and R⁶ is C₁-C₆alkyl-aryl.

In another subset of compounds, R⁵ and R⁶ are both C₁-C₆ alkyl.

In another subset of compounds, R⁵ is heterocyclyl and R⁶ is C₁-C₆alkyl.

Any and each individual definition of R⁵ and R⁶ as set out herein may becombined with any and each individual definition of X, R¹, R² and R³ asset out herein.

R⁷

In one subset of compounds, R⁷ is

-   -   1) CN,    -   2) halogen,    -   3) C₁-C₆ alkyl,    -   4) OC₁-C₆ alkyl,    -   5) C(O)OC₁-C₆ alkyl.    -   6) C(O)C₁-C₆ alkyl,    -   7) C(O) heteroaryl,    -   8) C(O)OH,    -   9) C(O)NH₂,    -   10) heterocyclyl,    -   11) heteroaryl,    -   12) C(OH) C₁-C₆ alkyl,    -   13) C(NH₂)═NH,    -   14) C(NH₂)═N—OH, or    -   15) C(NH₂)═N—OC(O) C₁-C₆ alkyl.

Any and each individual definition of R⁷ as set out herein may becombined with any and each individual definition of X, R¹, R² and R³asset out herein.

R⁸ and R⁹:

In one subset of compounds, both R⁸ and R⁹ are both C₁-C₆ alkyl.

In one subset of compounds, both R⁸ and R⁹ are both C₁-C₄ alkyl-C₃-C₆cycloakyl.

In an alternative subset of compounds, R⁸ is C₃-C₆ alkyl and R⁹ is C₁-C₄alkyl-C₃-C₆ cycloakyl.

Any and each individual definition of R⁸ and R⁹ as set out herein may becombined with any and each individual definition of X, R¹, R² and R³ asset out herein.

DEFINITIONS

Unless otherwise specified, the following definitions apply:

The singular forms “a”, “an” and “the” include corresponding pluralreferences unless the context clearly dictates otherwise.

As used herein, the term “comprising” is intended to mean that the listof elements following the word “comprising” are required or mandatorybut that other elements are optional and may or may not be present.

As used herein, the term “consisting of” is intended to mean includingand limited to whatever follows the phrase “consisting of”. Thus thephrase “consisting of” indicates that the listed elements are requiredor mandatory and that no other elements may be present.

As used herein, the term “alkyl” is intended to include both branchedand straight chain saturated aliphatic hydrocarbon groups having thespecified number of carbon atoms, for example, C₁-C₆ as in C₁-C₆ alkylis defined as including groups having 1, 2, 3, 4, 5 or 6 carbons in alinear or branched arrangement. Within this definition is, for exampleC₁-C₄ alkyl including groups having 1, 2, 3, or 4 carbons in a linear orbranched arrangement. Examples of C₁-C₆ alkyl as defined above include,but are not limited to, methyl, ethyl, n-propyl, i-propyl, n-butyl,t-butyl, i-butyl, pentyl, and hexyl. The term “alkyl” also includesC₃-C₇ alkyl which is defined as including 3, 4, 5, 6 or 7 carbons in alinear or branched arrangement.

As used herein, the term “alkenyl” is intended to mean unsaturatedstraight or branched chain hydrocarbon groups having the specifiednumber of carbon atoms therein, and in which at least two of the carbonatoms are bonded to each other by a double bond, and having either E orZ regeochemistry and combinations thereof. For example, C₂-C₆ as inC₂-C₆ alkenyl is defined as including groups having 1, 2, 3, 4, 5, or 6carbons in a linear or branched arrangement, at least two of the carbonatoms being bonded together by a double bond. Examples of C₂-C₆ alkenylinclude ethenyl (vinyl), 1-propenyl, 2-propenyl, 1-butenyl and the like.

As used herein, the term “alkynyl” is intended to mean unsaturated,straight chain hydrocarbon groups having the specified number of carbonatoms therein and in which at least two carbon atoms are bonded togetherby a triple bond. For example C₂-C₆ as in C₂-C₆ alkynyl is defined asincluding groups having 2, 3, 4, 5 or 6 carbon atoms in a chain, atleast two of the carbon atoms being bonded together by a triple bond.Examples of such alkynyls include ethynyl, 1-propynyl, 2-propynyl andthe like.

As used herein, the term “cycloalkyl” is intended to mean a monocyclicsaturated aliphatic hydrocarbon group having the specified number ofcarbon atoms therein, for example, C₃-C₇ as in C₃-C₇ cycloalkyl isdefined as including groups having 3, 4, 5, 6, or 7 carbons in amonocyclic arrangement. Within this definition is, for example, C₃-C₆cycloalkyl including groups having 3, 4, 5, or 6 carbons in a monocyclicarrangement. Examples of C₃-C₇ cycloalkyl as defined above include, butare not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl andcycloheptyl.

As used herein, the term “halo” or “halogen” is intended to meanfluorine, chlorine, bromine and iodine.

As used herein, the term “haloalkyl” is intended to mean an alkyl asdefined above, in which each hydrogen atom may be successively replacedby a halogen atom. Examples of haloalkyls include, but are not limitedto, CH₂F, CHF₂ and CF₃.

As used herein, the term “aryl”, either alone or in combination withanother radical, means a carbocyclic aromatic monocyclic groupcontaining 6 carbon atoms which may be further fused to a second 5- or6-membered carbocyclic group which may be aromatic, saturated orunsaturated. Aryl includes, but is not limited to, phenyl, indanyl,1-naphthyl, 2-naphthyl and tetrahydronaphthyl. The aryls may beconnected to another group either at a suitable position on thecycloalkyl ring or the aromatic ring.

As used herein, the term “heteroaryl” is intended to mean a monocyclicor bicyclic ring system of up to ten atoms, wherein at least one ring isaromatic, and contains from 1 to 4 hetero atoms selected from the groupconsisting of O, N, and S. The heteroaryl substituent may be attachedeither via a ring carbon atom or one of the heteroatoms. Examples ofheteroaryl groups include, but are not limited to thienyl,benzimidazolyl, benzo[b]thienyl, furyl, benzofuranyl, pyranyl,isobenzofuranyl, chromenyl, xanthenyl, 2H-pyrrolyl, pyrrolyl,imidazolyl, pyrazolyl, pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl,indolizinyl, isoindolyl, 3H-indolyl, indolyl, indazolyl, purinyl,4H-quinolizinyl, isoquinolyl, quinolyl, phthalazinyl, napthyridinyl,quinoxalinyl, quinazolinyl, cinnolinyl, pteridinyl, isothiazolyl,isochromanyl, chromanyl, isoxazolyl, furazanyl, indolinyl, isoindolinyl,thiazolo[4,5-b]-pyridine, and fluoroscein derivatives.

As used herein, the term “heterocycle”, “heterocyclic” or “heterocyclyl”is intended to mean a 5, 6, or 7 membered non-aromatic ring systemcontaining from 1 to 4 heteroatoms selected from the group consisting ofO, N and S. Examples of heterocycles include, but are not limited topyrrolidinyl, tetrahydrofuranyl, piperidyl, pyrrolinyl, piperazinyl,imidazolidinyl, morpholinyl, imidazolinyl, pyrazolidinyl, pyrazolinyl.

As used herein, the term “modulating the activity of melanocortin-4receptor” is intended to mean a compound which, upon binding to thereceptor, elicits a physiological response such as, but not limited to,regulation of food intake and energy expenditure. The compounds can beagonists, antagonists, partial agonists and inverse agonists. Generally,all diseases and disorders where the regulation of MC4R is involved canbe treated with the compounds described herein.

As used herein, the term “detectable label” is intended to mean a groupthat may be linked to a compound of Formula I to produce a probe or to amelanocortin-4 receptor, such that when the probe is associated with themelanocortin-4 receptor, the label allows either direct or indirectrecognition of the probe so that it may be detected, measured andquantified.

As used herein, the term “affinity tag” is intended to mean a ligand orgroup, which is linked to either a compound of Formula I or to amelanocortin-4 receptor to allow another compound to be extracted from asolution to which the ligand or group is attached.

As used herein, the term “probe” is intended to mean a compound ofFormula I, which is labeled with either a detectable label or anaffinity tag, and which is capable of binding, either covalently ornon-covalently, to a melanocortin-4 receptor. When, for example, theprobe is non-covalently bound, it may be displaced by a test compound.When, for example, the probe is bound covalently, it may be used to formcross-linked adducts, which may be quantified and inhibited by a testcompound.

As used herein, the term “optionally substituted with one or moresubstituents” or its equivalent term “optionally substituted with atleast one substituent” is intended to mean that the subsequentlydescribed event of circumstances may or may not occur, and that thedescription includes instances where the event or circumstance occursand instances in which it does not. The definition is intended to meanfrom zero to five substituents.

If the substituents themselves are incompatible with the syntheticmethods described herein, the substituent may be protected with asuitable protecting group (PG) that is stable to the reaction conditionsused in these methods. The protecting group may be removed at a suitablepoint in the reaction sequence of the method to provide a desiredintermediate or target compound. Suitable protecting groups and themethods for protecting and de-protecting different substituents usingsuch suitable protecting groups are well known to those skilled in theart; examples of which may be found in T. Greene and P. Wuts, ProtectingGroups in Chemical Synthesis (4th ed.), John Wiley & Sons, NY (2007),which is incorporated herein by reference in its entirety. Examples ofprotecting groups used throughout include, but are not limited to Fmoc,Bn, Boc, CBz and COCF₃. In some instances, a substituent may bespecifically selected to be reactive under the reaction conditions usedin the methods described herein. Under these circumstances, the reactionconditions convert the selected substituent into another substituentthat is either useful in an intermediate compound in the methodsdescribed herein or is a desired substituent in a target compound.

As used herein, the term “prodrug” is intended to mean a compound thatmay be converted under physiological conditions or by solvolysis to abiologically active compound of Formula I. Thus, the term “prodrug”refers to a precursor of a compound of Formula I that ispharmaceutically acceptable. A prodrug may be inactive or displaylimited activity when administered to a subject in need thereof, but isconverted in vivo to an active compound of Formula I. Typically,prodrugs are transformed in vivo to yield the compound of Formula I, forexample, by hydrolysis in blood or other organs by enzymatic processing.The prodrug compound often offers advantages of solubility, tissuecompatibility or delayed release in the subject (see, Bundgard, H.,Design of Prodrugs (1985), pp. 7-9, 21-24 (Elsevier, Amsterdam). Thedefinition of prodrug includes any covalently bonded carriers whichrelease the active compound described herein in vivo when such prodrugis administered to a subject. Prodrugs of a compound of Formula I may beprepared by modifying functional groups present in the compound ofFormula I in such a way that the modifications are cleaved, either inroutine manipulation or in vivo, to a parent compound of Formula I.

As used herein, the term “pharmaceutically acceptable salt” is intendedto mean both acid and base addition salts.

As used herein, the term “pharmaceutically acceptable acid additionsalt” is intended to mean those salts which retain the biologicaleffectiveness and properties of the free bases, which are notbiologically or otherwise undesirable, and which are formed withinorganic acids such as hydrochloric acid, hydrobromic acid, sulfuricacid, nitric acid, phosphoric acid and the like, and organic acids suchas acetic acid, trifluoroacetic acid, propionic acid, glycolic acid,pyruvic acid, oxalic acid, maleic acid, malonic acid, succinic acid,fumaric acid, tartaric acid, citric acid, benzoic acid, cinnamic acid,mandelic acid, methanesulfonic acid, ethanesulfonic acid,p-toluenesulfonic acid, salicylic acid, and the like.

As used herein, the term “pharmaceutically acceptable base additionsalt” is intended to mean those salts which retain the biologicaleffectiveness and properties of the free acids, which are notbiologically or otherwise undesirable. These salts are prepared fromaddition of an inorganic base or an organic base to the free acid. Saltsderived from inorganic bases include, but are not limited to, thesodium, potassium, lithium, ammonium, calcium, magnesium, iron, zinc,copper, manganese, aluminum salts and the like. Salts derived fromorganic bases include, but are not limited to, salts of primary,secondary, and tertiary amines, substituted amines including naturallyoccurring substituted amines, cyclic amines and basic ion exchangeresins, such as isopropylamine, trimethylamine, diethylamine,triethylamine, tripropylamine, ethanolamine, 2-dimethylaminoethanol,2-diethylaminoethanol, dicyclohexylamine, lysine, arginine, histidine,caffeine, procaine, hydrabamine, choline, betaine, ethylenediamine,glucosamine, methylglucamine, theobromine, purines, piperazine,piperidine, N-ethylpiperidine, polyamine resins and the like.

The compounds of Formula I, or their pharmaceutically acceptable saltsmay contain one or more asymmetric centers, chiral axes and chiralplanes and may thus give rise to enantiomers, diastereomers, and otherstereoisomeric forms and may be defined in terms of absolutestereochemistry, such as (R)- or (S)- or, as (D)- or (L)- for aminoacids. The present is intended to include all such possible isomers, aswell as, their racemic and optically pure forms. Optically active (+)and (−), (R)- and (S)-, or (D)- and (L)-isomers may be prepared usingchiral synthons or chiral reagents, or resolved using conventionaltechniques, such as reverse phase HPLC. The racemic mixtures may beprepared and thereafter separated into individual optical isomers orthese optical isomers may be prepared by chiral synthesis. Theenantiomers may be resolved by methods known to those skilled in theart, for example by formation of diastereoisomeric salts which may thenbe separated by crystallization, gas-liquid or liquid chromatography,selective reaction of one enantiomer with an enantiomer specificreagent. It will also be appreciated by those skilled in the art thatwhere the desired enantiomer is converted into another chemical entityby a separation technique, an additional step is then required to formthe desired enantiomeric form. Alternatively specific enantiomers may besynthesized by asymmetric synthesis using optically active reagents,substrates, catalysts, or solvents or by converting one enantiomer toanother by asymmetric transformation.

Certain compounds of Formula I may exist as a mix of epimers. Epimersmeans diastereoisomers that have the opposite configuration at only oneof two or more stereogenic centres present in the respective compound.

Certain compounds of Formula I may exist in Zwitterionic form and thepresent includes Zwitterionic forms of these compounds and mixturesthereof.

In addition, the compounds of Formula I also may exist in hydrated andanhydrous forms. Hydrates of the compound of any of the formulasdescribed herein are included. In a further embodiment, the compoundaccording to any of the formulas described herein is a monohydrate. Inone embodiment, the compounds described herein comprise about 10% orless, about 9% or less, about 8% or less, about 7% or less, about 6% orless, about 5% or less, about 4% or less, about 3% or less, about 2% orless, about 1% or less, about 0.5% or less, about 0.1% or less by weightof water. In another embodiment, the compounds described hereincomprise, about 0.1% or more, about 0.5% or more, about 1% or more,about 2% or more, about 3% or more, about 4% or more, about 5% or more,or about 6% or more by weight of water.

As used herein, the term “isotopes” is intended to mean that thecompounds of Formula I may exist in any isotopic composition,particularly deuterium analogs.

As used herein, the term “melanocortin-4 receptor” is intended to mean aG-protein coupled receptor encoded by the MC4R gene and that bindsmelanocortins, Agouti and Agouti-related protein.

As used herein, the term “therapeutically effective amount” is intendedto mean an amount of a compound of Formula I which, when administered toa subject is sufficient to effect treatment for a disease-state mediatedby a melanocortin-4 receptor. The amount of the compound of Formula Iwill vary depending on the compound, the condition and its severity, andthe age of the subject to be treated, but can be determined routinely byone of ordinary skill in the art having regard to his own knowledge andto this disclosure.

As used herein, the term “treating” or “treatment” is intended to meantreatment of a disease-state mediated by a melanocortin-4 receptor, asdisclosed herein, in a subject, and includes: (i) preventing a diseaseor condition mediated by a melanocortin-4 receptor from occurring in asubject, in particular, when such mammal is predisposed to the diseaseor condition but has not yet been diagnosed as having it; (ii)inhibiting a disease or condition mediated by a melanocortin-4 receptor,i.e., arresting its development; or (iii) relieving a disease/disorderor condition mediated by a melanocortin-4 receptor, i.e., causingregression of the condition.

As used herein, the term “treating obesity” is intended to mean theadministration of a pharmaceutical composition described herein to asubject, preferably a human, which is afflicted with obesity to cause analleviation of the obesity.

As used herein, the term “IC₅₀” is intended to mean an amount,concentration or dosage of a particular compound of Formula I thatachieves a 50% inhibition of a maximal agonist response.

As used herein, the term “EC₅₀” is intended to mean an amount,concentration or dosage of a particular compound of Formula I thatachieves a 50% of its maximal effect.

As used herein, the term “modulate” or “modulating” is intended to meanthe treatment, prevention, suppression, enhancement or induction of afunction or condition using the compounds as described herein. Forexample, the compounds as described herein can modulate melanocortin-4receptor function in a subject, thereby altering or regulating theactivity of melanocortin-4 receptor (MC4R) and consequently modifyingphysiological responses associated with MC4R such as, but not limitedto, food intake and energy expenditure. In this context, compounds asdescribed herein can elicit an effect useful for the treatment ofcachexia, eating disorders, diabetes, metabolic diseases, erectileand/or sexual dysfunction.

3. Utilities

The compounds as described herein are useful as melanocortin-4 receptormodulating compounds and as such the compounds, compositions and methodsdescribed herein include application to the cells or subjects afflictedwith or having a predisposition towards developing a particular diseasestate, which is mediated by a melanocortin-4 receptor. Thus, thecompounds, compositions and methods are used to treatdiseases/disorders, which include, but are not limited to, obesity,cachexia, eating disorders, diabetes, metabolic diseases, erectile andsexual dysfunction.

The treatment involves administration to a subject in need thereof acompound of Formula I or a pharmaceutically acceptable salt thereof, ora pharmaceutical composition comprising a pharmaceutical carrier and atherapeutically effective amount of a compound of Formula I, or apharmaceutically acceptable salt thereof. In particular, the compounds,compositions and methods described herein are useful in the treatment ofobesity, cachexia, eating disorders, diabetes, metabolic diseases,erectile and/or sexual dysfunction.

The compounds described herein, or their pharmaceutically acceptablesalts or their prodrugs, may be administered in pure form or in anappropriate pharmaceutical composition, and can be carried out via anyof the accepted modes of Galenic pharmaceutical practice.

The pharmaceutical compositions described herein can be prepared bymixing a compound of described herein with an appropriatepharmaceutically acceptable carrier, diluent or excipient, and may beformulated into preparations in solid, semi-solid, liquid or gaseousforms, such as tablets, capsules, powders, granules, ointments,solutions, suppositories, injections, inhalants, gels, microspheres, andaerosols. Typical routes of administering such pharmaceuticalcompositions include, without limitation, oral, topical, transdermal,inhalation, parenteral (subcutaneous injections, intravenous,intramuscular, intrasternal injection or infusion techniques),sublingual, ocular, rectal, vaginal, and intranasal. Pharmaceuticalcompositions described herein are formulated so as to allow the activeingredients contained therein to be bioavailable upon administration ofthe composition to a subject. Compositions that will be administered toa subject or patient take the form of one or more dosage units, wherefor example, a tablet may be a single dosage unit, and a container of acompound described herein in aerosol form may hold a plurality of dosageunits. Actual methods of preparing such dosage forms are known, or willbe apparent, to those skilled in this art; for example, see Remington'sPharmaceutical Sciences, 18th Ed., (Mack Publishing Company, Easton,Pa., 1990). The composition to be administered will, in any event,contain a therapeutically effective amount of a compound describedherein, or a pharmaceutically acceptable salt thereof, for treatment ofa disease-state as described above.

A pharmaceutical composition described herein may be in the form of asolid or liquid. In one aspect, the carrier(s) are particulate, so thatthe compositions are, for example, in tablet or powder form. Thecarrier(s) may be liquid, with the compositions being, for example, anoral syrup, injectable liquid or an aerosol, which is useful in, forexample inhalatory administration.

For oral administration, the pharmaceutical composition is typically ineither solid or liquid form, where semi-solid, semi-liquid, suspensionand gel forms are included within the forms considered herein as eithersolid or liquid.

As a solid composition for oral administration, the pharmaceuticalcomposition may be formulated into a powder, granule, compressed tablet,pill, capsule, chewing gum, wafer or the like form. Such a solidcomposition will typically contain one or more inert diluents or ediblecarriers. In addition, one or more of the following may be present:binders such as carboxymethylcellulose, ethyl cellulose,microcrystalline cellulose, gum tragacanth or gelatin; excipients suchas starch, lactose or dextrins, disintegrating agents such as alginicacid, sodium alginate, Primogel, corn starch and the like; lubricantssuch as magnesium stearate or Sterotex; glidants such as colloidalsilicon dioxide; sweetening agents such as sucrose or saccharin; aflavoring agent such as peppermint, methyl salicylate or orangeflavoring; and a coloring agent.

When the pharmaceutical composition is in the form of a capsule, e.g., agelatin capsule, it may contain, in addition to materials of the abovetype, a liquid carrier such as polyethylene glycol or oil such assoybean or vegetable oil.

The pharmaceutical composition may be in the form of a liquid, e.g., anelixir, syrup, solution, emulsion or suspension. The liquid may be fororal administration or for delivery by injection, as two examples. Whenused for oral administration, a typical composition contain, in additionto the present compounds, one or more of a sweetening agent,preservatives, dye/colorant and flavor enhancer. In a compositionintended to be administered by injection, one or more of a surfactant,preservative, wetting agent, dispersing agent, suspending agent, buffer,stabilizer and isotonic agent may be included.

The liquid pharmaceutical compositions described herein, whether they besolutions, suspensions or other like form, may include one or more ofthe following adjuvants: sterile diluents such as water for injection,saline solution, preferably physiological saline, Ringer's solution,isotonic sodium chloride, fixed oils such as synthetic mono ordiglycerides which may serve as the solvent or suspending medium,polyethylene glycols, glycerin, propylene glycol or other solvents;antibacterial agents such as benzyl alcohol or methyl paraben;encapsulating agents such as cyclodextrins or functionalizedcyclodextrins, including, but not limited to, α, β orδ-hydroxypropylcyclodextins or Captisol; antioxidants such as ascorbicacid or sodium bisulfite; chelating agents such as ethylenediaminetetraacetic acid; buffers such as acetates, citrates or phosphates andagents for the adjustment of tonicity such as sodium chloride ordextrose. The parenteral preparation can be enclosed in ampoules,disposable syringes or multiple dose vials made of glass or plastic. Aninjectable pharmaceutical composition is typically sterile.

A liquid pharmaceutical composition may be used for either parenteral ororal administration should contain an amount of a compound describedherein such that a suitable dosage will be obtained. Typically, thisamount is at least 0.01% of a compound described herein in thecomposition. When intended for oral administration, this amount may bevaried to be between 0.1 and about 70% of the weight of the composition.For parenteral usage, compositions and preparations described herein areprepared so that a parenteral dosage unit contains between 0.01 to 10%by weight of the compound described herein. Pharmaceutical compositionsmay be further diluted at the time of administration; for example aparenteral formulation may be further diluted with a sterile, isotonicsolution for injection such as 0.9% saline, 5 wt % dextrose (D5W),Ringer's solution, or others.

The pharmaceutical composition described herein may be used for topicaladministration, in which case the carrier may suitably comprise asolution, emulsion, ointment or gel base. The base, for example, maycomprise one or more of the following: petrolatum, lanolin, polyethyleneglycols, bee wax, mineral oil, diluents such as water and alcohol, andemulsifiers and stabilizers. Thickening agents may be present in apharmaceutical composition for topical administration. If intended fortransdermal administration, the composition may include a transdermalpatch or iontophoresis device. Topical formulations may contain aconcentration of the compound described herein from about 0.1 to about10% w/v (weight per unit volume).

The pharmaceutical composition described herein may be used for rectaladministration of a suppository, which will melt in the rectum andrelease the drug. The composition for rectal administration may containan oleaginous base as a suitable nonirritating excipient. Such basesinclude, without limitation, lanolin, cocoa butter and polyethyleneglycol.

The pharmaceutical composition described herein may include variousmaterials, which modify the physical form of a solid or liquid dosageunit. For example, the composition may include materials that form acoating shell around the active ingredients. The materials that form thecoating shell are typically inert, and may be selected from, forexample, sugar, shellac, and other enteric coating agents.Alternatively, the active ingredients may be encased in a gelatincapsule.

The pharmaceutical composition described herein in solid or liquid formmay include an agent that binds to the compound described herein andthereby assists in the delivery of the compound. Suitable agents thatmay act in this capacity include, but are not limited to, a monoclonalor polyclonal antibody, a protein or a liposome.

The pharmaceutical composition described herein may consist of dosageunits that can be administered as an aerosol. The term aerosol is usedto denote a variety of systems ranging from those of colloidal nature tosystems consisting of pressurized packages. Delivery may be by aliquefied or compressed gas or by a suitable pump system that dispensesthe active ingredients. Aerosols of compounds described herein may bedelivered in single phase, bi-phasic, or tri-phasic systems in order todeliver the active ingredient(s). Delivery of the aerosol includes thenecessary container, activators, valves, subcontainers, and the like,which together may form a kit. One skilled in the art, without undueexperimentation may determine preferred aerosols.

The pharmaceutical compositions described herein may be prepared bymethodology well known in the pharmaceutical art. For example, apharmaceutical composition intended to be administered by injection canbe prepared by mixing a compound described herein with sterile,distilled water so as to form a solution. A surfactant may be added tofacilitate the formation of a homogeneous solution or suspension.Surfactants are compounds that non-covalently interact with the compounddescribed herein so as to facilitate dissolution or homogeneoussuspension of the compound in the aqueous delivery system.

The compounds described herein, or their pharmaceutically acceptablesalts, may be administered in a therapeutically effective amount, whichwill vary depending upon a variety of factors including the activity ofthe specific compound employed; the metabolic stability and length ofaction of the compound; the age, body weight, general health, sex, anddiet of the patient; the mode and time of administration; the rate ofexcretion; the drug combination; the severity of the particular disorderor condition; and the subject undergoing therapy. Generally, atherapeutically effective daily dose may be from about 0.1 mg to about40 mg/kg of body weight per day or twice per day of a compound describedherein, or a pharmaceutically acceptable salt thereof.

4. Screening Assays

The compounds described herein may also be used in a method to screenfor other compounds that bind to a melanocortin-4 receptor. Generallyspeaking, to use the compounds described herein in a method ofidentifying compounds that bind to a melanocortin-4 receptor, thereceptor is bound to a support, and a compound described herein is addedto the assay. Alternatively, the compound may be bound to the supportand the receptor is added.

There are a number of ways in which to determine the binding of acompound described herein to the melanocortin-4 receptor. In one way,the compound, for example, may be fluorescently or radioactively labeledand binding determined directly. For example, this may be done byattaching the receptor to a solid support, adding a detectably labeledcompound, washing off excess reagent, and determining whether the amountof the detectable label is that present on the solid support. Numerousblocking and washing steps may be used, which are known to those skilledin the art.

In some cases, only one of the components is labeled. For example,specific residues in the receptor may be labeled. Alternatively, morethan one component may be labeled with different labels; for example,using ¹²⁵I for the receptor, and a fluorescent label for the probe.

The compounds described herein may also be used as competitors to screenfor additional drug candidates or test compounds. As used herein, theterms “drug candidate” or“test compounds” are used interchangeably anddescribe any molecule, for example, protein, oligopeptide, small organicmolecule, polysaccharide, polynucleotide, and the like, to be tested forbioactivity. The compounds may be capable of directly or indirectlyaltering the melanocortin-4 receptor biological activity.

Drug candidates can include various chemical classes, although typicallythey are small organic molecules having a molecular weight of more than100 and less than about 2,500 Daltons. Candidate agents typicallyinclude functional groups necessary for structural interaction withproteins, for example, hydrogen bonding and lipophilic binding, andtypically include at least an amine, carbonyl, hydroxyl, ether, orcarboxyl group. The drug candidates often include cyclical carbon orheterocyclic structures and/or aromatic or polyaromatic structuressubstituted with one or more functional groups.

Drug candidates can be obtained from any number of sources includinglibraries of synthetic or natural compounds. For example, numerous meansare available for random and directed synthesis of a wide variety oforganic compounds and biomolecules, including expression of randomizedoligonucleotides. Alternatively, libraries of natural compounds in theform of bacterial, fungal, plant and animal extracts are available orreadily produced. Additionally, natural or synthetically producedlibraries and compounds are readily modified through conventionalchemical, physical and biochemical means.

Competitive screening assays may be done by combining a melanocortin-4receptor and a probe to form a probe: receptor complex in a first samplefollowed by adding a test compound from a second sample. The binding ofthe test is determined, and a change or difference in binding betweenthe two samples indicates the presence of a test compound capable ofbinding to the receptor and potentially modulating the receptor'sactivity.

In one case, the binding of the test compound is determined through theuse of competitive binding assays. In this example, the probe is labeledwith a fluorescent label. Under certain circumstances, there may becompetitive binding between the test compound and the probe. Testcompounds which display the probe, resulting in a change in fluorescenceas compared to control, are considered to bind to the melanocortin-4receptor.

In one case, the test compound may be labeled. Either the test compound,or a compound described herein, or both, is added first to themelanocortin-4 receptor for a time sufficient to allow binding to form acomplex.

Formation of the probe:receptor complex typically require incubations ofbetween 4° C. and 40° C. for between 10 minutes to about 1 hour to allowfor high-throughput screening. Any excess of reagents are generallyremoved or washed away. The test compound is then added, and thepresence or absence of the labeled component is followed, to indicatebinding to the receptor.

In one case, the probe is added first, followed by the test compound.Displacement of the probe is an indication the test compound is bindingto the melanocortin-4 receptor and thus is capable of binding to, andpotentially modulating, the activity of the receptor. Either componentcan be labeled. For example, the presence of a probe in the washsolution indicates displacement by the test compound. Alternatively, ifthe test compound is labeled, the presence of the probe on the supportindicates displacement.

In one case, the test compound may be added first, with incubation andwashing, followed by the probe. The absence of binding by the probe mayindicate the test compound is bound to the melanocortin-4 receptor witha higher affinity. Thus, if the probe is detected on the support,coupled with a lack of test compound binding, may indicate the testcompound is capable of binding to the receptor.

Modulation is tested by screening for a test compound's ability tomodulate the activity of melanocortin-4 receptor and includes combininga test compound with the receptor, as described above, and determiningan alteration in the biological activity of the receptor. Therefore inthis case, the test compound should both bind to the receptor (althoughthis may not be necessary), and after its biological activity as definedherein.

Positive controls and negative controls may be used in the assays. Allcontrol and test samples are performed multiple times to obtainstatistically significant results. Following incubation, all samples arewashed free of non-specifically bound material and the amount of boundprobe determined. For example, where a radiolabel is employed, thesamples may be counted in a scintillation counter to determine theamount of bound compound.

Typically, the signals that are detected in the assay may includefluorescence, resonance energy transfer, time resolved fluorescence,radioactivity, fluorescence polarization, plasma resonance, orchemiluminescence and the like, depending on the nature of the label.Detectable labels useful in performing screening assays described hereininclude a fluorescent label such as Fluorescein, Oregon green, dansyl,rhodamine, tetramethyl rhodamine, Texas Red, Eu³⁺; a chemiluminescentlabel such as luciferase; colorimetric labels; enzymatic markers; orradioisotopes such as tritium, I¹²⁵ and the like

Affinity tags, which may be useful in performing the screening assaydescribed herein include biotin, polyhistidine and the like.

Synthesis and Methodology

General methods for the synthesis of the compounds are shown below andare disclosed merely for the purpose of illustration and are not meantto be interpreted as limiting the processes to make the compounds by anyother methods. Those skilled in the art will appreciate that a number ofmethods are available for the preparation of compounds described herein.

Schemes 1 to 8 illustrate general synthetic procedures for thepreparation of compounds described herein. Scheme 1 describes a generalsynthetic approach to the compounds 1-ix and 1-x as described herein.Ketone 1-iii is obtained by treatment of a 2-methyl pyridine compound1-i and an alkyl benzoate 1-ii in the presence of a base such as lithiumbis(trimethylsilyl)amide. Other methods known by those skilled in theart such as, but not limited to, the one described in Org. Synth. 2009,86, 18 can be used to afford compounds related to 1-iii. Oximeintermediate 1-iv can be obtained by treating ketone 1-iii withhydroxylamine-hydrochloride in the presence of a base. Treatment ofoxime 1-iv with trifluoroacetic anhydride in the presence of a base suchas triethylamine affords the azirine intermediate 1-v which is convertedto the pyrazolopyridine 1-vi upon heating in a microwave reactor using1,2-dichloroethane as solvent in the presence of a base. Failure to adda base such as N,N-diisopropylethylamine in the conversion of 1-v to1-vi typically results in bromide to chloride scrambling involving theparticipation of the solvent. It should be noted that othernon-chlorinated solvents were found sub-optimal for this reaction. Thereference cited above (i.e. Org. Synth. 2009, 86, 18) also describes asimilar sequence to the one used herein for the preparation ofpyrazolo[1,5-a]pyridines 1-vi from 1-iii (this reference providesexamples of compounds with different substitution patterns by comparisonto the compounds as described herein. Side-chain introduction leading to1-vii can be accomplished with reagents such as (E)-3-dimethylaminoacrylaldehyde and phosphoryl chloride. Other methods such as, but notlimited to, Organic Process Research & Development 2008, 12, 178 canalso be used. Compounds 1-viii are finally obtained by treatment ofaldehydes 1-vii with amine nucleophiles T²H and a reducing reagent suchas sodium triacetoxyborohydride. Various carbonylation methods known bythose skilled in the art can be used to convert 1-viii into 1-ix whichcan be hydrogenated under standard conditions to provide 1-x. Thecompounds 1-x can be obtained from olefinic compounds 1-ix usingalternative reduction methods such as diimide reduction or treatmentwith triethylsilane/trifluoroacetic acid. This is required when, forexample, the R⁷ substituent in olefins 1-ix is reactive to the standardhydrogenation reaction conditions (e.g when R⁷ is bromide or chloride).Alternatively the alkyl benzoate 1-ii can be replaced by an alkylacetate such as methyl tert-butylacetate and, following the samereaction sequence, compound 1-x in which the phenyl group is replaced bya t-butyl is obtained.

Scheme 2 describes another general synthetic approach to the compoundsas described herein. Compounds 2-vii are prepared by the followingsequence. Intermediates 2-i and 2-ii are reacted under the conditionsdescribed by A. B. Charette et. al in Organic Letters 2010, 12, 516 toprovide the pyrazolopyridine compounds 2-iii. Simple methods known bythose skilled in the art are used to introduce the amide side-chain in2-iv from the ester 2-iii (R=alkyl). As described above in Scheme 1,side-chain introduction leading to 2-v can be accomplished with reagentssuch as (E)-3-dimethylamino acrylaldehyde and phosphoryl chloride.Compounds 2-vi are finally obtained by treatment of aldehydes 2-v withan amine nucleophiles (T²H) and a reducing reagent such as sodiumtriacetoxyborohydride. The resulting compound 2-vi can be hydrogenatedunder standard conditions to provide 2-vii. The compounds 2-vii can beobtained using alternative methods such as diimide reduction when, forexample, the R⁴ substituent is reactive to the hydrogenation conditions.A subset of compounds, namely the bromides 2-vi (R⁷═Br) can be reactedwith tin reagent 2-viii in the presence of a palladium catalyst such aspalladium tetrakis(triphenylphosphine) to afford, after hydrolysis, themethyl ketone 2-x. Similarly, a methyl ester 2-ix can be obtained from2-vi (R⁷═Br) with palladium catalyst such as palladiumtetrakis(triphenylphosphine) and carbon monoxide in the presence ofmethanol.

Scheme 3 describes another general synthetic approach to the pyrimidinecompounds 3-xi and 3-xii described herein. First, the 3-aminopyrazolederivatives 3-iii are obtained via the condensation of ketonitriles 3-iand hydrazine (3-ii). According to a related procedure described inJournal of Medicinal Chemistry 1977, 20, 296, aminopyrazoles 3-iii arethen treated with acetylenedicarboxylate 3-iv to provide compounds 3-v.Phosphoryl chloride (3-vi) is then used to convert the alcohols 3-v tochlorides 3-vii and a catalytic hydrogenation on the latter, understandard conditions, allows the formation of pyrazolopyrimidine 3-viii.As described for the preparation of intermediate 2-iv above, standardprocedures are used to convert the alkyl ester 3-viii to the amides3-ix. Similarly, procedures similar to those described above were usedto prepare compounds 3-x and compounds as described herein 3-xi and3-xii.

Scheme 4 describes the synthesis of analogs bearing alkynyl as well asaryl side-chains. Typically, an halogen such as iodide is introduced onpyrazolopyridine intermediate 2-iv by treatment with N-iodosuccinimide(4-i). The resulting intermediate 4-ii is then treated with alkynes4-iii to provide compounds 4-iv described herein. The required alkynesare prepared using standard methods known by someone skilled in the art.For example, Example 97 as described in the Table below was preparedaccording to the reactions described in Scheme 4 and the requiredreagent 4-iii was (1-but-3-yn-1-yl)piperidine. The latter is simplyprepared from the commercially available alcohol by activation to amesylate and displacement with piperidine. Alternatively a Suzukicoupling is used on iodide 4-ii to prepare compounds 4-v describedherein.

Schemes 5-7 describe the synthesis of analogs of the compounds asdescribed herein that do not bear a substituted aryl attached to thepyrazolopyridine ring. The first step in Scheme 5 involves a reactiondescribed in the literature (e.g J. Med. Chem. 2001, 44, 2691) where theN-aminopyridinium intermediates 5-i is reacted with alkynedicarboxylates 5-ii to provide the diester intermediates 5-iii. Upontreatment in hot aqueous acid, the decarboxylated analogs 5-iv areobtained. Methods known by those skilled in the art are used tofunctionalize the carboxylic acid such as, for example, the formation ofamide 5-v on which the side chain is introduced using the same methodsdescribed for Schemes 1-3 to provide the compounds 5-vi as describedherein.

Scheme 6 describes the synthesis of the bromo intermediates 6-iv. TheN-aminopyridinium intermediate 5-i is treated with an alkylbromopropiolate 6-i to afford bromide intermediates 6-ii in low yield.The alkyl ester 6-ii is then hydrolyzed to the carboxylic acid 6-iiiwith an alkoxide such as lithium alkoxide. Upon heating, intermediates6-iii are decarboxylated to intermediates 6-iv. The side chain can beintroduced as above to provide the olefinic compounds as describedherein 6-v. Alternatively, the bromo intermediates 6-iv can be aminatedwith anilines 6-vi using methods known by those skilled in the art suchas, but not limited to, the Buchwald reaction conditions. Side-chainintroduction proceeds as above to provide compounds 6-viii as describedherein. The common intermediates 6-iv can also be involved in aSuzuki-type coupling with Pd catalyst to produce intermediates 6-ixwhich are derived as above to the compounds 6-x as described herein.

In Scheme 7, a Pd-catalyzed amination is carried out with intermediates6-ii and 6-vi. The resulting products 7-i are then hydrolyzed tointermediates 7-ii which are transformed to the compounds 7-iii asdescribed herein by using a standard peptide-type coupling procedureknown by those skilled in the art.

Scheme 8 describes the synthesis of compounds as described herein withother variations at the R³ group (in structure IA). Thus, as analternative to the carbonylation procedure described in Scheme 1, theintermediate 1-viii is subjected to an amination procedure to yield 8-iwhich can be reduced to compounds 8-ii as described above.Alternatively, compounds 8-iii are prepared by first treatingintermediates 1-x with a reagent such as oxalyl chloride followed by theaddition of nucleophiles such as, but not limited to, ammonia,methylamine and the sodium salt of hydrogen sulfide. Intermediates 1-x,after activation with oxalyl chloride, can be treated with an hydridesource to provide the benzylic amines 8-iv of the present invention.

EXAMPLES General

Analytical Reverse-Phase-HPLC Method:

Solvent A: MeOH:H₂O:TFA (5:95:0.05)

Solvent B: MeOH:H₂O:TFA (95:5:0.05)

Flow: 3.0 mL/min.

Gradient 0 to 100% Bin 2.0 min.

Column: ZorbaxC18, 3.5 microns, 4.6×30 mm

Wavelength 220 nm

LC-MS Method:

Solvent A: AcCN:H₂O:HCOOH (5:95:0.05)

Solvent B: AcCN:H₂O:HCOOH (95:5:0.05)

Gradient 0 to 100% B in 2.0 min.

Flow: 0.3 mL/min

Column: ZorbaxC18, 3.5 microns, 2.1×30 mm

Wavelength 220 nm

EXPERIMENTAL PROCEDURES Example 1

N,N-Dibutyl-2-(4-methoxyphenyl)-3-(3-(piperidin-1-yl)propyl)pyrazolo[1,5-a]pyridine-5-carboxamideIntermediate 1A

2-(4-Bromopyridin-2-yl)-1-(4-methoxyphenyl)ethanone

To a stirred solution of 4-bromo-2-methylpyridine (2.9 g, 16.8 mmol) andmethyl 4-methoxybenzoate (2.8 g, 16.8 mmol) in tetrahydrofuran (42 mL)at 0° C. was added dropwise a 1M solution of lithiumbis(trimethylsilyl)amide (33.6 mL, 33.6 mmol). The mixture was allowedto warm to room temperature and stirred for 3 days. A saturated solutionof ammonium chloride (40 mL) was added and the mixture was diluted withethyl acetate (50 mL). The separated aqueous layer was then extractedwith ethyl acetate (3×25 mL). The combined organic layers were washedwith brine, dried over anhydrous MgSO₄, filtered and concentrated underreduced pressure to afford a residue which was purified by automatedflash-chromatography (ethyl acetate/hexanes; 15/85). The title compoundwas obtained as a bright yellow solid (3.8 g, 75%). LCMS m/z 306.0;308.0 (M+H)⁺, ret. time=2.48 min.

Intermediate 1B

(Z)-2-(4-Bromopyridin-2-yl)-1-(4-methoxyphenyl)ethanone oxime

To a stirred solution of2-(4-bromopyridin-2-yl)-1-(4-methoxyphenyl)ethanone (3.8 g, 12.4 mmol)and N,N-diisopropylethylamine (5.4 mL, 31 mmol) in methanol (60 mL) atroom temperature was added hydroxylamine hydrochloride (1.7 g, 24.8mmol). The mixture was stirred at 60° C. for 2 days. After cooling toroom temperature, the precipitate formed was filtered and dried undervacuum to afford white needles (2.7 g, 68%). The material was used as isin the next step. LCMS m/z 321.0; 323.0 (M+H)⁺, ret. time=2.37 min.

Intermediate 1C

4-Bromo-2-(3-(4-methoxyphenyl)-2H-azirin-2-yl)pyridine

To a stirred solution of(Z)-2-(4-bromopyridin-2-yl)-1-(4-methoxyphenyl)ethanone oxime (2.7 g,8.4 mmol) and triethylamine (4.7 mL, 33.6 mmol) in dichloromethane at 0°C., was added trifluoroacetic anhydride (1.3 mL, 9.2 mmol). The mixturewas stirred at 0° C. for 20 minutes then at room temperature for 5hours. A saturated solution of ammonium chloride (20 mL) was added andthe mixture was diluted with dichloromethane (20 mL). The separatedaqueous layer was extracted with dichloromethane (3×25 mL). The combinedorganic layers were washed with brine, dried over anhydrous MgSO₄,filtered and concentrated under reduced pressure to afford a residuewhich was purified by automated flash-chromatography (ethylacetate/hexanes; 5/95). The title compound was obtained as a colorlesssolid (2.1 g, 83%); LCMS m/z 303.0, 305.0 (M+H)⁺, ret. time 2.57 min.

Intermediate 1D

5-Bromo-2-(4-methoxyphenyl)pyrazolo[1,5-a]pyridine

In a 20 mL microwave reactor was placed a solution of4-bromo-2-(3-(4-methoxyphenyl)-2H-azirin-2-yl)pyridine (1.3 g, 4.3 mmol)and N,N-diisopropylethylamine (375 μL, 2.2 mmol) in 1,2-dichloroethane(10 mL). The mixture was heated to 175° C. for 1 hour. The cooledmixture afforded a precipitate which was filtered and dried underreduced pressure to afford the title compound as a white solid (910 mg,70%). LCMS m/z 303.0, 305.0 (M+H)⁺, ret. time=2.88 min.

Intermediate 1E

(E)-N-(3-(5-Bromo-2-(4-methoxyphenyl)pyrazolo[1,5-a]pyridin-3-yl)allylidene)-N-methylmethanaminium

At 0° C., phosphoryl chloride (390 μL, 4.2 mmol) was added to a solutionof (E)-3-(dimethylamino)acrylaldehyde (420 μL, 4.2 mmol) in1,2-dichloroethane (5 mL) under a stream on nitrogen gas. After 5minutes at 0° C., a solution of5-bromo-2-(4-methoxyphenyl)pyrazolo[1,5-a]pyridine (640 mg, 2.1 mmol) in1,2-dichloroethane (5 mL) was added and the ice bath was removed. Themixture was heated to 65° C. for 2.5 h at which time monitoring thereaction by LC indicated all starting material had converted to thetitle compound. Upon cooling to room temperature, addition of waterresulted in the formation of a precipitate which was filtered and driedunder reduced pressure to afford the title compound as a solid (470 mg,57%). LCMS m/z 384.1, 386.1 M⁺, ret. time=2.17 min.

Intermediate 1F

(E)-3-(5-Bromo-2-(4-methoxyphenyl)pyrazolo[1,5-a]pyridin-3-yl)acrylaldehyde

To a stirred solution of(E)-N-(3-(5-bromo-2-(4-methoxyphenyl)pyrazolo[1,5-a]pyridin-3-yl)allylidene)-N-methylmethanaminium(470 mg, 1.22 mmol) in methanol (5 mL) was added a 15% solution ofpotassium bicarbonate (5 mL) and the mixture was stirred at roomtemperature for 1 h. Water was added and methanol was evaporated underreduced pressure. Filtration of the precipitate afforded 322 mg of thetitle compound. LCMS m/z 357.0, 359.0 (M+H)⁺, ret. time=2.70 min.

Intermediate 1G

(E)-5-Bromo-2-(4-methoxyphenyl)-3-(3-(piperidin-1-yl)prop-1-enyl)pyrazolo[1,5-a]pyridine

To a mixture of(E)-3-(5-bromo-2-(4-methoxyphenyl)pyrazolo[1,5-a]pyridin-3-yl)acrylaldehyde(385 mg, 1.1 mmol) and piperidine (160 μL, 1.6 mmol) in1,2-dichloroethane (5 mL) was added sodium triacetoxyborohydride (340mg, 1.6 mmol). The mixture and stirred at r.t for 2.5 h and a saturatedsolution of ammonium chloride (10 mL) was added. The separated aqueouslayer was then extracted with dichloromethane (3×25 mL). The combinedorganic layers were washed with brine, dried over anhydrous MgSO₄,filtered and concentrated under reduced pressure to afford a residuewhich was purified by automated flash-chromatography(methanol/dichloromethane; 15/85). The title compound was obtained as abright yellow solid (354 mg, 77%). LCMS m/z 426.1; 428.1 (weak)(M+H)⁺341.0; 343.0 (strong), ret time=2.15 min.

Intermediate 1H Example 12

(E)-N,N-Dibutyl-2-(4-methoxyphenyl)-3-(3-(piperidin-1-yl)prop-1-enyl)pyrazolo[1,5-a]pyridine-5-carboxamide

At room temperature in a 15-mL resealable vial, carbon monoxide wasbubbled for 5 min. through a solution of(E)-5-bromo-2-(4-methoxyphenyl)-3-(3-(piperidin-1-yl)prop-1-enyl)pyrazolo[1,5-a]pyridine(137 mg, 0.32 mmol), N,N-di-n-butylamine (215 μL, 1.3 mmol) andtriethylamine (0.5 mL) in toluene (2.5 mL). Palladiumbis(triphenylphosphine) dichloride (2 mg) was then added and carbonmonoxide was bubbled for an additional 5 min. at which time the vial wassealed and heated to 100° C. The mixture was heated to 100° C. for 12h., cooled to room temperature and evaporated under reduced pressure.The residue was dissolved in DMF, filtered and purified by RP-HPLC with30% Solvent B (0-3 min) then a gradient 30% to 100% Solvent B over 11minutes (Solvent A: MeOH:H₂O:TFA (5:95:0.05); Solvent B: MeOH:H₂O:TFA(95:5:0.05)) to afford, after freeze-drying overnight, 85 mg (50%) ofthe title compound as the TFA salt. LCMS m/z 503.3 (weak) (M+H)⁺, and418.3 (strong). ret time=2.30 min.

Example 1

N,N-Dibutyl-2-(4-methoxyphenyl)-3-(3-(piperidin-1-yl)propyl)pyrazolo[1,5-a]pyridine-5-carboxamide

A mixture of(E)-N,N-dibutyl-2-(4-methoxyphenyl)-3-(3-(piperidin-1-yl)prop-1-enyl)pyrazolo[1,5-a]pyridine-5-carboxamide(75 mg, 0.15 mmol) and 10% palladium on charcoal (7 mg) in a 1:1 mixtureof methanol:ethyl acetate was vigorously stirred under an atmosphere ofhydrogen for 12 h. The mixture was filtered through Celite andevaporated under reduced pressure. The residue was dissolved inN,N-dimethylformamide, filtered and purified by RP-HPLC with 30% SolventB (0-3 min) then a gradient 30% to 100% Solvent B over 11 minutes(Solvent A: MeOH:H₂O:TFA (5:95:0.05); Solvent B: MeOH:H₂O:TFA(95:5:0.05)) to afford, after freeze-drying overnight, 57 mg (75%) ofthe title compound as the TFA salt LCMS m/z 505.4 (M+H)⁺, ret. time=2.35min.

Note: The above reduction protocol was used to prepare all saturatedcompounds in the Table except for Examples 11, 37, 38, 45, 83. Compound11 was prepared as described below whereas compounds 37, 38, 45 and 83were prepared using the procedure described below for Example 83.

Example 11

2-(4-Chlorophenyl)-N,N-diisopentyl-3-(3-(piperidin-1-yl)propyl)pyrazolo[1,5-a]pyridine-5-carboxamide

A mixture of Example 10 (see Table 1) i.e.(E)-2-(4-chlorophenyl)-N,N-diisopentyl-3-(3-(piperidin-1-yl)prop-1-en-1-yl)pyrazolo[1,5-a]pyridine-5-carboxamide(60 mg, 0.09 mmol) and benzene sulphonylhydrazide (57 mg, 0.33 mmol) inN,N-dimethylformamide (1 mL) was heated to 100° C. for 12 h, cooled downto room temperature and diluted with saturated ammonium chloride (2 mL).The mixture was extracted with dichloromethane and the separated aqueouslayer was backextracted with dichloromethane (3×10 mL). The combinedorganic layers were washed with brine, dried over anhydrous MgSO₄,filtered and concentrated under reduced pressure to afford a residuewhich was purified by RP-HPLC with 30% Solvent B (0-3 min) then agradient 30% to 100% Solvent B over 11 minutes (Solvent A: MeOH:H₂O:TFA(5:95:0.05); Solvent B: MeOH:H₂O:TFA (95:5:0.05)) to afford, afterfreeze-drying overnight, 9.9 mg of the title compound as the TFA salt.LCMS m/z 537.3 (M+H)⁺, ret. time 2.60 min.

The following example was prepared using chemistry described in Scheme2:

Example 41

(E)-2-(4-Bromophenyl)-N,N-diisopentyl-3-(3-(piperidin-1-yl)prop-1-en-1-yl)pyrazolo[1,5-a]pyridine-5-carboxamideIntermediate 41A

Ethyl 2-(4-bromophenyl)pyrazolo[1,5-a]pyridine-5-carboxylate

Related procedures are described in Org. Lett. 2010, 12, 516):4-Ethoxycarbonyl-N-benzoyliminopyridinium ylid (JOC 2003, 68, 7119)(3.50 g, 13.0 mmol), para-tris-methoxyphenylphosphine (686 mg, 1.95mmol), Palladium (II) bromide (173 mg, 0.65 mmol), silver triflate (8.93g, 39.0 mmol) and (E)-1-Bromo-4-(2-iodovinyl)benzene (Org. Lett. 2008,10, 5485) (4.02 g, 13.0 mmol) were placed in a 250 mL round bottom flaskequipped a with magnetic stirrer. Dioxane (52 mL) was added. The mixturewas degassed by bubbling nitrogen for 10 minutes with vigorous stirringand heated to 125-130° C. for 15-20 h. The mixture was then cooled toroom temperature, diluted with CH₂Cl₂, filtered over Celite. The organiclayer was then washed with saturated aqueous sodium bicarbonate and theorganic phase was concentrated under reduced pressure. The crude productwas triturated with methanol to afford 2.40 g (54%) of the titlecompound. LCMS m/z 345.0, 347.0 (M+H)⁺, ret. time=3.05 min.

Intermediate 41B

2-(4-Bromophenyl)pyrazolo[1,5-a]pyridine-5-carboxylic acid

Ethyl 2-(4-bromophenyl)pyrazolo[1,5-a]pyridine-5-carboxylate (2.40 g,7.0 mmol) was dissolved in THF (50 mL) and water was added (12 mL)followed by LiOH—H₂O (877 mg, 20.9 mmol). The mixture was stirredovernight at room temperature and 1M HCl (ca 28 mL) was added. Themixture was extracted with EtOAc (2×25 mL) and the combined organiclayers were washed with brine, dried over anhydrous MgSO₄, filtered andconcentrated under reduced pressure to afford a crude white solid thatwas directly used into the next step. LCMS m/z 317.0, 319.0 (M+H)⁺, ret.time 2.62 min.

Intermediate 41C

2-(p-Bromophenyl)pyrazolo[1,5-a]pyridine-5-carboxylic diisopentylamide

2-(4-bromophenyl)pyrazolo[1,5-a]pyridine-5-carboxylic acid (2.20 g, 7.0mmol), diisopentylamine (2.13 mL, 1.64 g, 10.4 mmol) andhydroxybenzotriazole hydrate (1.59 g, 10.4 mmol) were dissolved in DMF(50 mL) and CH₂Cl₂ (25 mL) and1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (2.0 g, 10.4mmol) was added and the mixture was stirred at room temperatureovernight. A saturated solution of ammonium chloride (20 mL) was addedand the mixture was diluted with dichloromethane (20 mL). The separatedaqueous layer was then extracted with dichloromethane (3×25 mL). Thecombined organic layers were washed with brine, dried over anhydrousMgSO₄, filtered and concentrated under reduced pressure to afford aresidue which was purified by column chromatography using 20% to 30%EtOAc in hexanes as eluant to provide 2.89 g of the title compound. LCMSm/z 456.2, 4582 (M+H)⁺, ret. time=3.33 min.

Intermediate 41D

(E)-2-(4-Bromophenyl)-N,N-diisopentyl-3-(3-oxoprop-1-en-1-yl)pyrazolo[1,5-a]pyridine-5-carboxamide

Intermediate 41D was prepared from intermediate 41C using the proceduresfor the synthesis of Intermediates 1E and 1F above. LCMS m/z 510.2,512.2 (M+H)⁺, ret. time=3.19 min.

Example 41

(E)-2-(4-Bromophenyl)-N,N-diisopentyl-3-(3-(piperidin-1-yl)prop-1-en-1-yl)pyrazolo[1,5-a]pyridine-5-carboxamide

Example 41 was prepared from intermediate 41D using the proceduredescribed for the preparation of intermediate 1G. LCMS m/z 579.2; 581.2(weak) (M+H)⁺, 496.2 (strong) ret. time 2.54 min.

Example 42

(E)-2-(4-Acetylphenyl)-N,N-diisopentyl-3-(3-(piperidin-1-yl)prop-1-en-1-yl)pyrazolo[1,5-a]pyridine-5-carboxamide

To a mixture of Example 41i.e.(E)-2-(4-bromophenyl)-N,N-diisopentyl-3-(3-(piperidin-1-yl)prop-1-en-1-yl)pyrazolo[1,5-a]pyridine-5-carboxamide(553 mg, 0.954 mmol) in toluene (14 mL) was addedtributyl(1-ethoxy-vinyl)tin (1.03 g, 2.86 mmol) andtetrakis(triphenylphosphine) palladium (O) (55 mg, 0.05 mmol). Themixture was degassed by bubbling nitrogen into it for 10 minutes and wasthen heated to 120° C. for 4 h. The mixture was allowed to cool to roomtemperature and concentrated to a residue and dissolved in THF (12 mL).1N HCl (3 mL) was added and the mixture was stirred at room temperaturefor 1 h. Sodium bicarbonate was slowly added until pH was reached 8-9and the mixture was extracted with ethyl acetate (2×30 mL). The combinedorganics were washed with brine, filtered and concentrated under reducedpressure.

The residue was then purified by column chromatography using CH₂Cl₂,then 5% to 10% MeOH in CH₂Cl₂+2% Et₃N. The compound was further purifiedby preparative HPLC on a reverse-phase Zorbax SB-C18 column 21.2×100 mmeluted with MeOH-water-0.1% TFA. Isocratic 30% for 3 minutes thenGradient 30% to 100% MeOH over 14 minutes. LCMS m/z 543.4 (weak) (M+H)⁺;458.3 (strong). ret time=2.44 min.

Example 43

(E)-Methyl4-(5-(diisopentylcarbamoyl)-3-(3-(piperidin-1-yl)prop-1-en-1-yl)pyrazolo[1,5-a]pyridin-2-yl)benzoate

To a solution of Example 41i.e.(E)-2-(4-bromophenyl)-N,N-diisopentyl-3-(3-(piperidin-1-yl)prop-1-en-1-yl)pyrazolo[1,5-a]pyridine-5-carboxamide(275 mg, 0.474 mmol) in toluene (3 mL), MeOH (4 mL) and Et₃N (0.5 mL)was added tetrakis(triphenylphosphine) palladium (O) (27 mg, 0.024 mmol)and the mixture was degassed by bubbling carbon monoxide. The flask wassealed and heated to 75-80° C. for 48 h. The mixture was thenconcentrated and purified by column chromatography using CH₂Cl₂, then 5%MeOH in CH₂Cl₂+2% Et₃N. The compound was further purified by passingthrough a sulfonic acid silica gel column with 5% MeOH in CH₂Cl₂ andthen the compound was obtained using 1% NH₄OH in 10% MeOH in CH₂Cl₂ toafford 247 mg (93%) of ca 95% pure methylester. A fraction of thispurified product was then further purified by Prep HPLC as describedabove to afford the title compound. LCMS m/z 559.8 (weak) (M+H)⁺, 474.3(strong). ret. time=2.45 min.

Example 46

2-(4-(1-Hydroxyethyl)phenyl)-N,N-diisopentyl-3-(3-(piperidin-1-yl)propyl)pyrazolo[1,5-a]pyridine-5-carboxamide

(E)-2-(4-acetylphenyl)-N,N-diisopentyl-3-(3-(piperidin-1-yl)prop-1-en-1-yl)pyrazolo[1,5-a]pyridine-5-carboxamide(80 mg, 0.15 mmol) was dissolved in MeOH (3 mL) and triethylamine (1 mL)and 10% Pd/C (40 mg) was added. The vessel was flushed with 3 cycles ofvacuum then hydrogen from a balloon, and the reaction mixture wasstirred for 4 h at room temperature, filtered through Celite andevaporated. The residue was purified by preparative HPLC on areverse-phase Zorbax SB-C18 column 21.2×100 mm eluted withMeOH-water-0.1% TFA. Isocratic 30% for 3 minutes then Gradient 30% to100% MeOH over 14 minutes. LCMS m/z 547.4 (weak) (M+H)⁺, 458.3 (strong).ret. time=2.35 min.

Example 47

2-(4-Acetylphenyl)-N,N-diisopentyl-3-(3-(piperidin-1-yl)propyl)pyrazolo[1,5-a]pyridine-5-carboxamide

To a solution of2-(4-(1-hydroxyethyl)phenyl)-N,N-diisopentyl-3-(3-(piperidin-1-yl)propyl)pyrazolo[1,5-a]pyridine-5-carboxamide(35 mg, 0.053 mmol) in chloroform (1 mL) was added activated manganesedioxide (92 mg, 1.06 mmol,) and the mixture was heated to 50° C. for 24h. The reaction mixture was then diluted with dichloromethane andfiltered through a 0.45 um filter, concentrated and then purified bypreparative HPLC on a reverse-phase Zorbax SB-C18 column 21.2×100 mmeluted with MeOH-water-0.1% TFA. Isocratic 30% for 3 minutes thenGradient: 30% to 100% MeOH over 14 minutes. LCMS m/z 545.4 (M+H)⁺, ret.time=2.45 min.

Example 83

2-(3-Chlorophenyl)-N,N-diisopentyl-3-(3-(piperidin-1-yl)propyl)pyrazolo[1,5-a]pyridine-5-carboxamide

In a 15 mL sealed tube were added compound of Example 72i.e.(E)-2-(3-chlorophenyl)-N,N-diisopentyl-3-(3-(piperidin-1-yl)prop-1-en-1-yl)pyrazolo[1,5-a]pyridine-5-carboxamide(160 mg, 0.299 mmol), trifluoroacetic acid (0.069 ml, 0.896 mmol), andtriethylsilane (0.143 ml, 0.896 mmol) in chloroform (5 ml) and themixture was heated to 80-100° C. overnight, cooled down to roomtemperature and assayed for conversion by HPLC/LCMS. LC indicatedhomogenous peak but LCMS indicated the presence of both olefin andsaturated compounds. Then 140 μL of TFA and 280 μL of triethylsilanewere added and the mixture was heated to 100° C. for 5 days and cooldown to room temperature. Saturated sodium bicarbonate was slowly addedand the separated organic layer was washed with brine and dried oversodium sulfate, filtered and evaporated under reduced pressure. Thecrude material was dissolved in DMF and purified on a reverse-phaseZorbax SB-C18 column 21.2×100 mm and was eluted with MeOH-water-0.1%TFA. Isocratic 30% for 3 minutes then Gradient: 30% to 100% MeOH over 14minutes. LCMS m/z 537.3 (M+H)⁺, ret. time=2.55 min.

Example 88

(E)-N,N-Diisopentyl-2-(4-methoxyphenyl)-3-(3-(piperidin-1-yl)prop-1-en-1-yl)pyrazolo[1,5-a]pyrimidine-5-carboxamideIntermediate 88A

3-(4-Methoxyphenyl)-1H-pyrazol-5-amine

To a solution of 3-(4-methoxyphenyl)-3-oxopropanenitrile (5.0 g, 28.5mmol) in ethanol (100 mL) was added hydrazine hydrate (2.8 mL, 57.1mmol) at room temperature. The mixture was heated to reflux for 8 h,allowed to cool and concentrated under reduced pressure to about ¼volume (25 mL). The resulting precipitate was allowed to stir overnightat room temperature, filtered and rinsed with ethanol (2 mL). The titleproduct was dried under vacuum. Yield 4.15 g (77%); LCMS m/z 190.1(M+H)⁺, ret. time=1.56 min.

Intermediate 88B

Ethyl7-hydroxy-2-(4-methoxyphenyl)pyrazolo[1,5-a]pyrimidine-5-carboxylate

Diethyl acetylenedicarboxylate (883 μL, 5.6 mmol) was added to asolution of 3-(4-methoxyphenyl)-1H-pyrazol-5-amine (1.1 g, 5.6 mmol) inacetic acid (5 mL). The very thick mixture was allowed to stand at roomtemperature with occasional stirring for 3 h. Ethyl acetate (5 mL) andhexanes (15 mL) were added and the precipitate was filtered, and driedunder high vacuum. Yield: 1.26 g (76%); LCMS m/z 314.1 (M+H)⁺, ret.time=2.25 min.

Intermediate 88C

Ethyl7-chloro-2-(4-methoxyphenyl)pyrazolo[1,5-a]pyrimidine-5-carboxylate

Ethyl7-hydroxy-2-(4-methoxyphenyl)pyrazolo[1,5-a]pyrimidine-5-carboxylate(1.26 g; 4.03 mmol) was suspended in phosphoryl chloride (8 mL; 88 mmol)and the mixture was heated to 115° C. for 1 h. The reaction mixture wasallowed to cool to room temperature and then carefully quenched into acold mixture of methylene chloride and saturated sodium bicarbonate. Thebasic aqueous layer was back extracted once with methylene chloride andthe combined organic phases were washed with brine. Concentrationafforded a crude solid which was triturated in methanol (15 mL) at 60°C. for 5 min. and then at room temperature for an hour. Filtrationafforded 808 mg (60%) of the title compound. LCMS m/z 332.1 (M+H)⁺, ret.time=2.77 min.

Intermediate 88D

Ethyl 2-(4-methoxyphenyl)pyrazolo[1,5-a]pyrimidine-5-carboxylate

To a solution of ethyl7-chloro-2-(4-methoxyphenyl)pyrazolo[1,5-a]pyrimidine-5-carboxylate (767mg; 2.31 mmol) in methylene chloride (10 mL), methanol (10 mL) andtriethylamine (2 mL) was added 10% Pd on carbon (77 mg) and the mixturewas cooled to 0° C. The reaction flask was put under vacuum and thenhydrogen was introduced using a balloon. A second cycle of vacuum andhydrogen purge was performed and the mixture was stirred at 0° C. for1.5 h. The mixture was flushed with two cycles of vacuum and nitrogen,diluted with methylene chloride and then filtered through a 0.45 micronfilter to remove the catalyst. Concentration afforded the crude productwhich was triturated in methanol (25 mL) and filtered to afford 485 mg(71%) of the title compound. LCMS m/z 298.1 (M+H)⁺, ret. time=2.53 min.

Intermediate 88E

2-(4-Methoxyphenyl)pyrazolo[1,5-a]pyrimidine-5-carboxylic acid

To a solution of ethyl2-(4-methoxyphenyl)pyrazolo[1,5-a]pyrimidine-5-carboxylate (485 mg; 1.63mmol) in THF (10 mL) and water (3 mL) was added lithium hydroxidehydrate (206 mg; 4.9 mmol) and the mixture was stirred at roomtemperature for 3 hours. Concentrated hydrochloric acid was then slowlyadded (ca. 0.5 mL) until pH reached 1 and the mixture was concentratedunder reduced pressure. The resulting solid was dissolved in methylenechloride, filtered, concentrated and dried under high vacuum. The crudeproduct was used directly in the next step. LCMS m/z 270.1 (M+H)⁺, ret.time=2.20 min.

Intermediate 88F

N,N-Diisopentyl-2-(4-methoxyphenyl)pyrazolo[1,5-a]pyrimidine-5-carboxamide

To a solution of2-(4-methoxyphenyl)pyrazolo[1,5-a]pyrimidine-5-carboxylic acid in DMF(10 mL) and methylene chloride (5 mL) was added diisopentylamine (0.67mL; 512 mg; 3.3 mmol) and hydroxybenzotriazole monohydrate (499 mg; 3.3mmol). The mixture was stirred for 10 min. at room temperature and1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (626 mg;3.3 mmol) was added. The mixture was stirred overnight at roomtemperature. An additional amount of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride was then added (626 mg; 3.3 mmol) and thereaction mixture was heated to 50° C. for 30 min. The mixture was thencooled to room temperature, diluted with methylene chloride andsaturated ammonium chloride was added. The aqueous layer was backextracted with methylene chloride and the combined organics were washedwith water (3×10 mL) and brine. Concentration afforded a crude oil thatwas purified by flash-chromatography using first 100% methylene chloridethen 5% methanol in methylene chloride to afford an oil that solidifiedunder vacuum. This solid was taken into hot methanol (7 mL) and, uponcooling, a solid formed. Water (3 mL) was then added slowly andfiltration afforded 590 mg (89%) of the title compound. LCMS m/z 409.3(M+H)⁺, ret. time=3.08 min.

Intermediate 88G

(E)-N,N-Diisopentyl-2-(4-methoxyphenyl)-3-(3-oxoprop-1-en-1-yl)pyrazolo[1,5-a]pyrimidine-5-carboxamide

To a solution of 3-(dimethylamino)acrolein (0.22 mL; 218 mg; 2.2 mmol)in N,N-dimethylformamide (3 mL) was added phosphoryl chloride (0.16 mL;269 mg; 1.76 mmol) and the mixture was stirred at room temperature for10 min. ThenN,N-diisopentyl-2-(4-methoxyphenyl)pyrazolo[1,5-a]pyrimidine-5-carboxamide(180 mg; 0.44 mmol) in N,N-dimethylformamide (2 mL) was added and themixture was heated to 65° C. for 4 h. Then triethylamine (2 mL) andwater (2 mL) were slowly added at 60° C. and the mixture was stirred for30 min. The mixture was cooled to room temperature and diluted withmethylene chloride and water. The aqueous layer was back extracted withmethylene chloride and the combined organic layers were washed withwater (3×10 mL), brine and concentrated. The residue was purified byflash-chromatography using 5% methanol in methylene chloride as eluant.LCMS m/z 463.3 (M+H)⁺, ret. time=2.98 min.

Example 88

(E)-N,N-Diisopentyl-2-(4-methoxyphenyl)-3-(3-(piperidin-1-yl)prop-1-en-1-yl)pyrazolo[1,5-a]pyrimidine-5-carboxamide

The title compound was synthesized from(E)-N,N-diisopentyl-2-(4-methoxyphenyl)-3-(3-oxoprop-1-en-1-yl)pyrazolo[1,5-a]pyrimidine-5-carboxamideusing a procedure similar to the one described above for synthesis ofintermediate 1G. LCMS m/z 532.4 (weak); 447.3 (strong) (M+H)⁺, ret.time=2.45 min.

Example 89

N,N-Diisopentyl-2-(4-methoxyphenyl)-3-(3-(piperidin-1-yl)propyl)pyrazolo[1,5-a]pyrimidine-5-carboxamide

The title compound was prepared from(E)-N,N-diisopentyl-2-(4-methoxyphenyl)-3-(3-(piperidin-1-yl)prop-1-en-1-yl)pyrazolo[1,5-a]pyrimidine-5-carboxamideusing a procedure similar to the one described above for the synthesisof intermediate 88D. LCMS m/z 534.4 (M+H)⁺, ret. time=2.44 min.

Example 141

N,N-diisopentyl-2-(morpholine-4-carbonyl)-3-(3-(piperidin-1-yl)propyl)pyrazolo[1,5-a]pyridine-5-carboxamideIntermediate 141A

diethyl5-(diisopentylcarbamoyl)pyrazolo[1,5-a]pyridine-2,3-dicarboxylate

To a suspension of1-amino-4-(diisopentylcarbamoyl)pyridin-1-ium-2,4-(dinitro)phenolate(Intermediate 142B) (1 g, 2.167 mmol) and potassium carbonate (0.599 g,4.33 mmol) in THF (5 ml) at 0° C. was added diethyl but-2-ynedioate(0.249 ml, 2.383 mmol). The mixture was stirred at 0° C. for 1 h then at22° C. for 12 hours. The mixture was diluted with water and extractedwith ethyl acetate (3×25 ml). The combined organics were washed withbrine, dried over Na₂SO₄, filtered and concentrated. The residue waspurified by flash chromatography: ISCO gold 40 g eluting with 10% to100% ethyl acetate in hexanes over 12 min. Pooled and concentrateddesired fractions to afford, 0.48 g (50%) of the title compound as a tancoloured oil. LCMS m/z 445.7 (M+H)⁺. ret. time 2.49 min.

Intermediate 141B

5-(diisopentylcarbamoyl)pyrazolo[1,5-a]pyridine-2-carboxylic acid

Diethyl5-(diisopentylcarbamoyl)pyrazolo[1,5-a]pyridine-2,3-dicarboxylate (0.35g, 0.786 mmol) was added to 40% aqueous sulphuric acid (5 ml) andstirred at reflux for 3 h. The resulting suspension was cooled in an icebath then extracted with ethyl acetate (3×25 ml). The combined organiclayers were washed with brine and concentrated to afford, 0.29 g (98%)of the title compound as a white solid. LCMS m/z 346.2 (M+H)⁺. ret.time=2.57 min.

Intermediate 141C

N,N-diisopentyl-2-(morpholine-4-carbonyl)pyrazolo[1,5-a]pyridine-5-carboxamide

5-(diisopentylcarbamoyl)pyrazolo[1,5-a]pyridine-2-carboxylic acid (0.29g, 0.840 mmol), EDC (0.274 g, 1.427 mmol) and HOBT (0.219 g, 1.427 mmol)were combined in DMF (2.0 ml). Added triethylamine (0.351 ml, 2.52 mmol)and morpholine (0.073 ml, 0.840 mmol) and stirred at 22° C. for 12 h.The mixture was diluted with ethyl acetate (25 ml) and washed withwater, saturated sodium bicarbonate solution and brine, dried overNa₂SO₄, filtered and concentrated. The residue was purified by flashchromatography: ISCO Gold 24 g using 0% to 100% ethyl acetate in hexanesover 11 min. Pooled and concentrated desired fractions to afford, 0.26 g(74%) of the title compound as a clear oil. LCMS m/z 415.3 (M+H)⁺. ret.time=2.27 min.

Intermediate 141D

(E)-N,N-diisopentyl-2-(morpholine-4-carbonyl)-3-(3-oxoprop-1-en-1-yl)pyrazolo[1,5-a]pyridine-5-carboxamide

To a stirred solution of dimethylacroleine (0.250 ml, 2.52 mmol) andPOCl₃ (0.235 ml, 2.52 mmol) in dichloroethane (2 ml) at 0° C. for 15 minwas addedN,N-diisopentyl-2-(piperidine-1-carbonyl)pyrazolo[1,5-a]pyridine-5-carboxamide(0.26 g, 0.630 mmol). The mixture was heated to 65° C. for 6 h. Mixedmore reagents for 15 min then added to solution above and stirred at 65°C. for 12 h. Water (20 ml) was added to the cooled mixture and extractedwith DCM (3×25 ml). The combined organics (liquids and solids) wereconcentrated to afford a red semisolid. The residue was treated withsaturated sodium bicarbonate (20 ml) and MeOH (20 ml) overnight. Thesuspension was neutralized with a saturated NH₄Cl solution and extractedwith DCM (3×100 ml). The combined organics were dried over Na₂SO₄,filtered and concentrated. The residue was purified by flashchromatography: ISCO 24 g eluting with 0% to 100% ethyl acetate inhexanes over 12 min. Pooled and concentrated desired fractions toafford, 0.23 g (78%) of the title compound as a yellow oil. LCMS m/z469.3 (M+H)⁺. ret. time=2.29 min

Example 141E

(E)-N,N-diisopentyl-2-(morpholine-4-carbonyl)-3-(3-(piperidin-1-yl)prop-1-en-1-yl)pyrazolo[1,5-a]pyridine-5-carboxamide

To a stirred suspension of(E)-N,N-diisopentyl-2-(morpholine-4-carbonyl)-3-(3-oxoprop-1-en-1-yl)pyrazolo[1,5-a]pyridine-5-carboxamide(115 mg, 0.245 mmol) and piperidine (0.049 ml, 0.491 mmol) indichloroethane (5 ml) was added sodium triacetoxyborohydride (104 mg,0.491 mmol). After 12 h, 1M aqueous NaOH (25 mL) was added and themixture was extracted with DCM (3×25 mL). The organic layers were driedover Na₂SO₄, filtered and concentrated. The residue was purified by prepHPLC with 20% Solvent B (0-3 min) then a gradient 20% to 100% Solvent Bover 13 minutes (Solvent A: MeOH:H₂O:TFA (5:95:0.05); Solvent B:MeOH:H₂O:TFA (95:5:0.05)) to afford, after concentration of desiredfractions, 115 mg (71%) of the title compound as the TFA salt. LCMS m/z538.4 (M+H)⁺ (weak) and 453.2 (strong) ret. time=2.11 min.

Example 141

N,N-diisopentyl-2-(morpholine-4-carbonyl)-3-(3-(piperidin-1-yl)propyl)pyrazolo[1,5-a]pyridine-5-carboxamide

A stirred suspension of((E)-N,N-diisopentyl-2-(morpholine-4-carbonyl)-3-(3-(piperidin-1-yl)prop-1-en-1-yl)pyrazolo[1,5-a]pyridine-5-carboxamide(100 mg, 0.186 mmol) and 10% Pd/C (10 mg, 9.40 μmol) in MeOH (5 ml) waspurged and stirred under a hydrogen atmosphere. After 12 h the mixturewas filtered, concentrated and purified by prep HPLC with 20% Solvent B(0-3 min) then a gradient 20% to 100% Solvent B over 13 minutes (SolventA: MeOH:H₂O:TFA (5:95:0.05); Solvent B: MeOH:H₂O:TFA (95:5:0.05)) toafford, after concentration of desired fractions, 66 mg (52%) of thetitle compound as the TFA salt. LCMS m/z 540.4 (M+H)⁺ ret. time=2.11min.

Example 142

N,N-diisopentyl-2-((4-methoxyphenyl)amino)-3-(3-(piperidin-1-yl)propyl)pyrazolo[1,5-a]pyridine-5-carboxamideIntermediate 142A

N,N-diisopentylisonicotinamide

To a stirred solution of diisopentylamine (5.0 ML, 24.7 mmol) andtriethylamine (9.4 mL, 67.4 mmol) in dichloromethane (23 mL) at 0° C.was added slowly isonicotinoyl chloride hydrochloride (4 g, 22.5 mmol).The mixture was allowed to warm to room temperature and stirred at roomtemperature for 2 hours. The mixture was diluted with saturated sodiumbicarbonate and the separated aqueous layer was extracted with methylenechloride (3×25 mL). The combined organics were washed with water (10mL), brine, dried (anh. sodium sulfate), filtered and evaporated. Theresidue solidified upon standing to afford 4.7 g of an orange solid.LCMS m/z 263.2 (M+H)⁺.

Intermediate 142B

1-amino-4-(diisopentylcarbamoyl)pyridin-1-ium

The reaction conditions reported by Charette in J. Org. Chem. 2003, 68,7119 were used: A solution of N,N-diisopentylisonicotinamide (1.0 g, 3.8mmol) and O-(2,4-dinitrophenyl)hydroxylamine (1.043 g, 4.19 mmol) inacetonitrile was stirred at 40° C. for 12 hours. The mixture was allowedto cool, concentrated and the residue was triturated in ether overnight.The resulting solid was filtered and dried to afford N-aminopyridinium2,4-(dinitro)phenolate (1.4 g, 3.03 mmol, 80% yield) as a yellow solid.LCMS m/z 278.2 (M+H)⁺.

Intermediate 142C

methyl2-bromo-5-(diisopentylcarbamoyl)pyrazolo[1,5-a]pyridine-3-carboxylate

A suspension of N-aminopyridinium 2,4-(dinitro)phenolate (10 g, 21.67mmol), methyl 3-bromopropiolate (3.12 ml, 26.0 mmol) and potassiumcarbonate (5.99 g, 43.3 mmol) in degassed DMF (75 ml) was stirred at 0°C. for 5 minutes and at 22° C. for 18 h. The mixture was diluted withethyl acetate (100 mL) and washed with water (3×25 mL), brine, driedover anhydrous sodium sulfate, filtered and concentrated. The residuewas purified by flash chromatography on silica gel (120 g, 0% to 100%ethyl acetate/hexanes over 19 min). to provide methyl2-bromo-5-(diisopentylcarbamoyl)pyrazolo[1,5-a]pyridine-3-carboxylate(0.52 g, 1.186 mmol, 5.47% yield). LCMS m/z 438.4, 440.1 (M+H)⁺.

Intermediate 142D

2-bromo-5-(diisopentylcarbamoyl)pyrazolo[1,5-a]pyridine-3-carboxylicacid

To a stirred solution of methyl2-bromo-5-(diisopentylcarbamoyl)pyrazolo[1,5-a]pyridine-3-carboxylate(0.47 g, 1.072 mmol) in THF (15 ml) and MeOH (15 ml) was added 2Maqueous LiOH solution (10.00 ml, 20 mmol). The mixture was stirred at30° C. for 4 h then concentrated partially, acidified with 1N HCl andextracted with ethyl acetate (3×40 ml). The combined organics were driedover anhydrous sodium sulphate, filtered and concentrated. The orangesolid was triturated with methyl tert-butyl ether (10 ml) to afford2-bromo-5-(diisopentylcarbamoyl)pyrazolo[1,5-a]pyridine-3-carboxylicacid (0.291 g, 0.679 mmol, 63.3% yield) LCMS m/z 424.1, 426.1 (M+H)⁺,ret. time=2.21 min.

Intermediate 142E

2-bromo-N,N-diisopentylpyrazolo[1,5-a]pyridine-5-carboxamide

A solution of2-bromo-5-(diisopentylcarbamoyl)pyrazolo[1,5-a]pyridine-3-carboxylicacid (0.285 g, 0.672 mmol) in diphenyl ether (6 ml) was heated to 210°C. for 9 hours. The mixture was allowed to cool, loaded on a silica gelpad, rinsed with diethyl ether (10 mL) and dried thoroughly undervacuum. The dried silica gel pad was then connected to a 24 g silica gelISCO Gold cartridge and eluted with hexanes for 3 min then 0% to 100%ethyl acetate over 11 min. Concentration of the desired fractionsafforded 2-bromo-N,N-diisopentylpyrazolo[1,5-a]pyridine-5-carboxamide(0.19 g, 0.475 mmol, 70.7% yield) as a yellow oil. LCMS m/z 380.1, 382.1(M+H)⁺

Intermediate 142F

(E)-2-bromo-N,N-diisopentyl-3-(3-(piperidin-1-yl)prop-1-en-1-yl)pyrazolo[1,5-a]pyridine-5-carboxamide

Starting from intermediate 142E, The intermediate 142F was obtainedfollowing procedures 1E, 1F and 1G described above. LCMS m/z 503.2,505.2 (M+H)⁺

Intermediate 142G Example 138

(E)-N,N-diisopentyl-2-((4-methoxphenyl)amino)-3-(3-(piperidin-1-yl)prop-1-en-1-yl)pyrazolo[1,5-a]pyridine-5-carboxamide

In a sealed tube 4-methoxyaniline (18.34 mg, 0.149 mmol),tris(dibenzylideneacetone)dipalladium (4.55 mg, 4.97 μmol) and(9,9-dimethyl-9H-xanthene-4,5-diyl)bis(diphenylphosphine) (5.75 mg, 9.93μmol) were added to a suspension of(E)-2-bromo-N,N-diisopentyl-3-(3-(piperidin-1-yl)prop-1-en-1-yl)pyrazolo[1,5-a]pyridine-5-carboxamide(50 mg, 0.099 mmol) and potassium phosphate, dibasic (57.1 mg, 0.328mmol) in toluene (5 ml). The mixture was heated at 110° C. overnight.The reaction mixture was cooled to room temperature, diluted with waterand extracted with ethyl acetate (3×25 mL). The combined organics werewashed with brine, dried over anh. sodium sulfate, filtered andconcentrated. The residue was purified by SCX (silica-gel supportedsulfonic acid) then by preparative HPLC (20% to 100% MeOH in water(0.05% TFA) in 7 minutes) to affordN,N-diisopentyl-2-((4-methoxyphenyl)amino)-3-(3-(piperidin-1-yl)prop-1-en-1-yl)pyrazolo[1,5-a]pyridine-5-carboxamide.LCMS m/z 546.4 (M+H)⁺ weak, 461.3 (strong); ret. time=2.19 min.

Example 142

N,N-diisopentyl-2-((4-methoxyphenyl)amino)-3-(3-(piperidin-1-yl)propyl)pyrazolo[1,5-a]pyridine-5-carboxamide

The hydrogenation procedure described for Example 1 was followed using(E)-N,N-diisopentyl-2-((4-methoxyphenyl)amino)-3-(3-(piperidin-1-yl)prop-1-en-1-yl)pyrazolo[1,5-a]pyridine-5-carboxamide.LCMS m/z 548.4 (M+H)⁺; ret. time=2.19 min.

Example 149

N,N-diisopentyl-2-(4-methoxyphenyl)-3-(2-(piperidin-1-yl)ethyl)pyrazolo[1,5-a]pyridine-5-carboxamideIntermediate 149A

N-((5-bromo-2-(4-methoxyphenyl)pyrazolo[1,5-a]pyridin-3-yl)methylene)-N-methylmethanaminiumchloride

To a stirred suspension of5-bromo-2-(4-methoxyphenyl)pyrazolo[1,5-a]pyridine (200 mg, 0.66 mmol)in 1,2-dichloroethane (6 mL) was addedN-(Chloromethylene)-N-methylmethanaminium chloride (195 mg, 1.5 mmol).The mixture was stirred at 20° C. for 20 h then heated to 50° C. for 1 hat which time monitoring the reaction by LC indicated all startingmaterial had converted to the title compound. The solids were collectedby filtration and dried under reduced pressure to afford the titlecompound as a solid (260 mg, 100%). LCMS m/z 331.0, 333.0(M-(CH₃)₂NH+H₂O)⁺, ret. time=2.13 min.

Intermediate 149B

5-bromo-2-(4-methoxyphenyl)pyrazolo[1,5-a]pyridine-3-carbaldehyde

To a stirred solution ofN-((5-bromo-2-(4-methoxyphenyl)pyrazolo[1,5-a]pyridin-3-yl)methylene)-N-methylmethanaminiumchloride (260 mg, 0.66 mmol) in methanol (3 mL) was added a 3% solutionof potassium bicarbonate (3.1 mL) and the mixture was stirred at roomtemperature for 2 h. The solids were collected by filtration and driedunder reduced pressure to afford the title compound as a solid (201 mg,92%). LCMS m/z 331.0, 333.0 (M+H)⁺, ret. time=2.13 min.

Intermediate 149C

5-bromo-2-(4-methoxyphenyl)-3-(2-methoxyvinyl)pyrazolo[1,5-a]pyridine

To a solution of methoxymethyltriphenylphosphonium chloride (298 mg,0.87 mmol) in methanol (3 ml) was added a solution of sodium methoxide25% wt. in methanol (0.20 ml, 0.87 mmol). The resulting white suspensionwas stirred at 20° C. for 30 minutes. The mixture was concentrated todryness and azeotroped with toluene (6 ml) twice. The resulting solidwas suspended in toluene (2 ml). A suspension of5-bromo-2-(4-methoxyphenyl)pyrazolo[1,5-a]pyridine-3-carbaldehyde (180mg, 0.54 mmol) in toluene (4 ml) was added to the ylide suspension.Heated the resulting mixture to 85-90° C. and stirred for 1.25 h. Cooledto 20° C. and stirred 17.5 h. In a separate flask, to a solution ofmethoxymethyltriphenylphosphonium chloride (298 mg, 0.87 mmol) inmethanol (3 ml) was added a solution of sodium methoxide 25% wt. inmethanol (0.20 ml, 0.87 mmol). The resulting white suspension wasstirred for 30 minutes, concentrated and azeotroped with toluene (6 ml)twice. The resulting solid was suspended in toluene (2 ml) and added tothe reaction mixture which was heated to 90° C. for 2 h at which timemonitoring the reaction by LC indicated all starting material hadconverted to the title compound. to the mixture was cooled to 20° C.,filtered through a 0.45 μm filter and rinsed with toluene (2 mL). Thefiltrate was concentrated under reduced pressure to afford a residuethat was purified by automated ISCO chromatography (ethylacetate/hexane; 25/75). The title compound was obtained as a brightyellow solid (168 mg, 86%). LCMS m/z 359.0 (M+H)⁺, ret. time=2.31 (cisisomer) and 2.34 min (trans isomer).

Intermediate 149D

2-(5-bromo-2-(4-methoxyphenyl)pyrazolo[1,5-a]pyridin-3-yl)acetaldehyde

To a stirred solution of5-bromo-2-(4-methoxyphenyl)-3-(2-methoxyvinyl)pyrazolo[1,5-a]pyridine(160 mg, 0.45 mmol) in THF (7.3 ml) was added a 4N HCl solution in water(2.45 ml, 9.8 mmol). Heated to 50° C. and stirred for 4 h at which timemonitoring the reaction by LC indicated all starting material hadconverted to the title compound. The solution was cooled to 20° C. and asaturated solution of sodium bicarbonate (10 mL) and ethyl acetate (15mL) were added The organic layer was dried over anhydrous MgSO4,filtered and concentrated to dryness to afford a residue that waspurified by automated ISCO chromatography (ethylacetate/dichloromethane; 7/93). The title compound was obtained as a tansolid (43 mg, 28%). LCMS m/z 345.0, 347.0 (M+H)⁺, ret. time=2.02, 2.12min. Peak at 2.01 is hydrate of the aldehyde LCMS m/z 363.1, 365.1(M+H)⁺ and peak at 2.12 is methyl hemiacetal of the aldehyde LCMS m/z377.1, 379.1 (M+H)⁺ both formed under LCMS conditions.

Intermediate 149E

5-bromo-2-(4-methoxyphenyl)-3-(2-(piperidin-1-yl)ethyl)pyrazolo[1,5-a]pyridine

To a solution of2-(5-bromo-2-(4-methoxyphenyl)pyrazolo[1,5-a]pyridin-3-yl)acetaldehyde(40 mg, 0.12 mmol) and piperidine (23 μl, 0.23 mmol) in1,2-dichloroethane (3.5 ml) was added sodium triacetoxyborohydride (49m, 0.23 mmol). The reaction mixture was stirred at 20° C. for 17 h. Thereaction mixture was diluted with dichloromethane (10 mL) and washedwith a 5% sodium bicarbonate solution (6 mL). The organic layer wasdried over anhydrous MgSO4, filtered and concentrated under reducedpressure to give a residue that was purified by automated ISCOchromatography (methanol/dichloromethane; 5/95). The title compound wasobtained as a white solid (28 mg, 58%). LCMS m/z 414.1, 416.1 (M+H)⁺,ret. time=1.76 min.

Example 149

N,N-diisopentyl-2-(4-methoxyphenyl)-3-(2-(piperidin-1-yl)ethyl)pyrazolo[1,5-a]pyridine-5-carboxamide

At room temperature in a 15-mL resealable vial, carbon monoxide wasbubbled for 5 min. through a solution of5-bromo-2-(4-methoxyphenyl)-3-(2-(piperidin-1-yl)ethyl)pyrazolo[1,5-a]pyridine(28 mg, 0.068 mmol), diisopentylamine (42 μL, 0.20 mmol) andtriethylamine (188 μL, 1.35 mmol) in toluene (3.5 mL). Palladiumbis(triphenylphosphine) dichloride (4.7 mg, 6.8 μmol) was then added andcarbon monoxide was bubbled for an additional 5 min. at which time thevial was sealed and heated to 100° C. for 66 h., cooled down to roomtemperature and evaporated under reduced pressure. The residue wasdissolved in DMF, filtered and purified by RP-HPLC with 30% Solvent B(0-3 min) then a gradient 30% to 100% Solvent B over 12 minutes (SolventA: MeOH:H₂O:TFA (5:95:0.05); Solvent B: MeOH:H₂O:TFA (95:5:0.05)) toafford, after freeze-drying overnight, 34 mg (80%) of the title compoundas the TFA salt. LCMS m/z 519.4 (M+H)⁺, ret. time=2.12 min.

Example 164

N,N-diisopentyl-2-(6-methoxypyridin-3-yl)-3-(3-(piperidin-1-yl)propyl)pyrazolo[1,5-a]pyridine-5-carboxamideIntermediate 164A

(E)-N,N-diisopentyl-2-(6-methoxypyridin-3-yl)-3-(3-(piperidin-1-yl)prop-1-en-1-yl)pyrazolo[1,5-a]pyridine-5-carboxamide

To a solution of(E)-2-bromo-N,N-diisopentyl-3-(3-(piperidin-1-yl)prop-1-en-1-yl)pyrazolo[1,5-a]pyridine-5-carboxamide(Intermediate 142F) (30 mg, 0.060 mmol) and(6-methoxypyridin-3-yl)boronic acid (10.94 mg, 0.071 mmol) indimethoxyethane (2 ml) was added a 2M sodium carbonate solution (0.089ml, 0.179 mmol) and palladium tetrakis triphenylphosphine (6.88 mg, 5.96μmol). The mixture was heated to 80° C. for 12 h. More palladium cat(6.88 mg, 5.96 μmol) was added and the mixture was heated an extra 12 h.The cooled mixture was extracted with ethyl acetate (3×25 ml), driedover anhydrous Na₂SO₄, filtered and concentrated. The residue waspurified by RP-HPLC with 20% Solvent B (0-3 min) then a gradient 20% to100% Solvent B over 13 minutes (Solvent A: MeOH:H₂O:TFA (5:95:0.05);Solvent B: MeOH:H₂O:TFA (95:5:0.05)) to afford, after concentration ofdesired fractions, 9 mg (20%) of the title compound as the TFA salt.LCMS m/z 532.4 (weak) (M+H)⁺, and 447.3 (strong). ret. time=2.06 min.

Example 164

N,N-diisopentyl-2-(6-methoxypyridin-3-yl)-3-(3-(piperidin-1-yl)propyl)pyrazolo[1,5-a]pyridine-5-carboxamide

The hydrogenation procedure described for Example 1 was followed using(E)-N,N-diisopentyl-2-(6-methoxypyridin-3-yl)-3-(3-(piperidin-1-yl)prop-1-en-1-yl)pyrazolo[1,5-a]pyridine-5-carboxamide.LCMS m/z 534.5 (M+H)⁺; ret. time=2.16 min.

Example 165

N,N-diisopentyl-N′-methyl-2-phenyl-3-(3-(piperidin-1-yl)propyl)pyrazolo[1,5-a]pyridine-5-carboximidamide

At room temperature, oxalyl chloride (0.26 mL, 3.0 mmol) was added toN,N-diisopentyl-2-phenyl-3-(3-(piperidin-1-yl)propyl)pyrazolo[1,5-a]pyridine-5-carboxamide(75 mg, 0.15 mmol) in dichloromethane (1 mL) and the mixture was heatedto 50° C. for 20 minutes and was then poured into 1.5 mL of 2Nmethylamine in methanol. The mixture was evaporated under reducedpressure and the residue was dissolved in DMF, filtered and purified byRP-HPLC with 30% Solvent B (0-3 min) then a gradient 30% to 100% SolventB over 12 minutes (Solvent A: MeOH:H₂O:TFA (5:95:0.05); Solvent B:MeOH:H₂O:TFA (95:5:0.05)) to afford, after freeze-drying overnight, 65mg (59%) of the title compound as the TFA salt. LCMS m/z 516.4 (M+H)⁺,ret. time=1.82 min.

TABLE 1 Analytical HPLC retention time, LCMS data and IC₅₀ data(Activity range for IC₅₀ values: A < 500 nM; 500 nM < B < 1000 nM; 1000nM < C < 5000 nM; 5000 < D < 15000 nM) MS: HPLC RT (M + H)⁺ Cpd (min)see No Structure analytical footnote* IC₅₀  1

2.03 505.4 C  2

2.15 533.4 C  3

2.14 531.3 (weak) and 446.3 (strong)* B  4

2.30 559.4 C  5

2.30 557.4 (weak) and 472.3 (strong)* C  6

2.29 543.4 (weak) and 472.3 (strong)* C  7

2.22 444.3 (weak) and 472.3 (strong)* D  8

2.26 545.4 C  9

2.20 517.4 D  10

2.19 535.3 (weak) and 450.2 (strong)* B  11

2.20 537.3 C  12

2.04 503.3 (weak) and 418.3 (strong)* C  13

2.14 531.4 (weak) and 446.3 (strong)* B  14

2.09 561.4 (weak) and 476.3 (strong)* A  15

2.14 533.4 A  16

2.11 563.4 A  17

2.12 491.3 (weak) and 446.3 (strong)* D  18

2.14 493.4 D  19

2.17 531.4 (weak) and 446.3 (strong)* C  20

2.14 545.4 (weak) and 460.3 (strong)* C  21

2.17 533.4 C  22

2.15 547.4 B  23

2.17 517.3 (weak); 446.3 (strong)* C  24

2.11 545.7 (weak); 460.3 (strong)* C  25

1.97 489.3 (weak) and 404.2 (strong)* C  26

1.91 487.3 (weak) and 402.2 (strong)* D  27

1.90 489.3 D  28

2.22 579.2; 581.2 (weak) and 494.2; 496.2 (strong)* C  29

2.12 543.4* B  30

2.16 559.7* A  31

2.16 561.7 A  32

2.11 547.8 B  33

2.14 545.4 A  34

2.13 579.2; 581.2 (weak) and 494.2; 496.2 (strong)* C  35

2.13 543.4* C  36

2.07 559.4* C  37

2.24 581.2; 583.2 A  38

2.14 581.2; 583.2 C  39

2.09 561.3 C  40

2.10 545.3 C  41

2.22 579.2; 581.2 (weak) and 494.2; 496.2 (strong)* C  42

2.12 543.4 (weak) and 458.3* B  43

2.18 559.4 (weak) and 474.3* B  44

2.19 561.3 B  45

2.26 581.2 and 583.2 A  46

2.14 547.4 A  47

2.14 545.3 B  48

2.03 493.3 B  49

2.14 521.4 A  50

2.16 521.4 C  51

2.06 491.3 (weak); 406.2 (strong)* C  52

2.16 519.4 (weak); 434.3 (strong)* B  53

2.18 519.4 (weak); 434.3 (strong)* C  54

2.00 475.3 B  55

2.13 503.4 C  56

2.16 503.4 B  57

2.02 473.3 (weak); 388.2 (strong)* C  58

2.11 501.4 (weak); 416.3 (strong)* B  59

2.12 501.4 (weak); 416.3 (strong)* C  60

2.08 489.4 B  61

2.19 517.4 A  62

2.22 517.4 C  63

2.09 587.4 (weak); 402.3 (strong)* B  64

2.18 515.4 (weak); 430.3 (strong)* A  65

2.20 515.4 (weak); 430.3 (strong)* C  66

1.99 565.4 B  67

2.11 593.4 A  68

2.16 593.4 B  69

2.00 563.4 (weak); 473.3 (strong)* B  70

2.26 591.4 (weak); 506.3 (strong)* A  71

2.26 591.4 (weak); 506.3 (strong)* C  72

2.19 535.3 (weak); 450.2 (strong)* B  73

2.14 545.3 (weak); 460.3 (strong)* C  74

2.14 547.3 C  75

2.13 547.4 C  76

2.26 607.3 (weak); 522.3 (strong)* C  77

2.05 544.4 (weak); 459.3 (strong)* A  78

2.07 519.4 A  79

2.19 581.7 (weak); 460.3 (strong)* D  80

2.20 583.4 D  81

2.19 613.4 (weak); 460.3 (strong)* D  82

2.19 615.4 D  83

2.20 535.3 A  84

2.16 561.4 (weak); 476.3 (strong)* A  85

2.06 533.4 (weak); 448.3 (strong)* B  86

2.16 563.4 A  87

2.06 535.4 C  88

2.11 532.4 (weak); 447.3 (strong)* C  89

2.13 534.4 C  90

2.05 546.4 A  91

2.02 544.3 (weak); 459.3 (strong)* B  92

2.11 528.4 A  93

2.19 494.2; 496.2* D  94

2.11 571.4 B  95

2.03 546.4 A  96

2.12 528.4 A  97

2.17 577.3 C  98

2.10 571.4 C  99

2.08 518.3 (weak); 447.3 (strong)* C 100

2.09 520.3 (weak); 447.3 (strong)* D 101

2.14 563.3* A 102

1.91 561.4 A 103

2.12 587.4 B 104

2.11 520.4 D 105

2.13 522.4 D 106

2.16 545.4 (weak); 446.3 (strong)* C 107

2.06 603.4 A 108

2.04 527.3 (weak); 442.3 (strong)* C 109

2.16 529.4 (weak); 444.3 (strong)* C 110

2.16 547.4 D 111

2.15 547.4 C 112

2.14 549.4 C 113

2.16 565.3 (weak) 480.2 (strong) C 114

2.16 567.4 C 115

2.10 458.2* C 116

2.18 553.3 C 117

2.15 574.4 C 118

2.08 549.4 C 119

2.18 483.4 A 120

1.90 545.4 A 121

2.11 547.4 C 122

2.22 616.4 C 123

2.09 533.3 (weak); 446.3 (strong)* C 124

2.15 535.4 A 125

2.24 618.4 C 126

1.70 545.4 A 127

1.85 502.4 B 128

2.18 482.4 (weak); 396.3 (strong)* C 129

2.03 562.4 B 130

2.07 529.4 B 131

2.22 505.4 D 132

2.41 505.2 (weak) 420.2 (strong)* C 133

2.10 659.4 D 134

2.37 647.4 C 135

2.22 585.4 A 136

2.32 639.4 C 137

2.22 615.3 C 138

2.19 546.4 (weak) 461.3 (strong) A 139

2.27 648.4 A 140

2.32 679.4 D 141

2.02 540.4 D 142

2.19 548.4 A 143

2.17 519.3 C 144

1.73 489.4 D 145

2.18 545.4 (weak); 446.3 (strong)* A 146

2.20 547.4 C 147

2.17 547.4 (weak); 460.3 (strong)* D 148

1.62 491.4 D 149

2.12 519.4 D 150

2.22 553.4 (weak); 446.3 (strong)* D 151

2.01 533.4 C 152

2.19 576.8 B 153

2.13 477.3 (weak); 446.3 (strong)* D 154

2.17 465.3 D 155

2.23 555.4 C 156

2.13 505.4 C 157

2.13 479.3 D 158

2.14 549.4 (weak); 446.3 (strong)* C 159

2.13 547.4 (weak); 446.3 (strong)* B 160

2.17 561.4 C 161

2.17 551.4 C 162

2.15 549.4 B 163

2.18 507.4 C 164

2.16 534.5 A 165

1.82 516.4 A 166

2.19 549.4 C 167

1.98 538.4 (weak); 453.2 (strong)* D 168

2.12 547.4 B 169

2.17 545.4 (weak); 446.3 (strong)* B *Typically, the allylic andproargylic amines in the Table showed weak or no protonated molecularion in the mass spectra. Instead a strong peak corresponding to afragment was observed (e.g. M⁺—amine moiety) IC₅₀ data (Activity rangefor IC50 values: A < 500 nM; 500 nM < B < 1000 nM; 1000 nM < C < 5000nM); 5000 < D < 15000 nM)

TABLE 2 The following compounds are further contemplated Structure

Assays

To test the ability of a compound to modulate the stability, activity,and/or cell surface localization of an MC4R polypeptide, a labeled orunlabeled test compound is brought in contact with the MC4R protein or afragment thereof and the amount of the test compound bound to the MC4Rprotein or to the fragment thereof is measured. This can be achieved forexample as follows:

-   -   (a) contacting a first cell with a test compound for a time        period sufficient to allow the cell to respond to said contact        with the test compound;    -   (b) determining/measuring the conformational stability,        activity, and/or cell surface localization of a MC4R polypeptide        (or a fragment thereof comprising a ligand binding domain) in        the cell (or on the cell surface) contacted in step (a); and        comparing the stability, activity, and/or cell surface        localization of the MC4R polypeptide determined in step (b) to        that of an MC4R polypeptide in a control cell that has not been        contacted with the test compound; wherein a detectable change in        the stability, activity, and/or cell surface localization of the        MC4R polypeptide in the first cell in response to contact with        the test compound compared to the stability level of the MC4R        polypeptide in the control cell that has not been contacted with        the test compound, indicates that the test compound modulates        the stability of the MC4R polypeptide and is a candidate        compound for the treatment of a disorder associated with reduced        MC4R stability or activity. The cell can either be a host cell        transformed with a non-endogenous wild-type or mutant MC4R, or        an endogenously-MC4R-expressing cell, including mutant and        wild-type MC4Rs. Such cells include the “obesity neurons” such        as GTI-7 cells, described above, those described in MacKenzie et        al., Current Medicinal Chemistry-Immunology, Endocrine &        Metabolic Agents 2004; 4: 113-117, which endogenously express        MC4R, or transformed cells expressing normal or mutated, tagged        MC4R such as the HEK293 cells described in Blondet et al., J        Biochem 2004; 135: 541-546.        Cyclic AMP Assay

Intracellular cyclic 3′-5′ adenosine monophosphate (cAMP) accumulationwas measured using a competitive immunoassay based on HTRF (HomogeneousTime-Resolved Fluorescence) technology (cAMP dynamic-2, Cis-Bio).

HEK293T stable cell line expressing double-tagged WT-hMC4R constructwere collected and washed in cAMP buffer (1XD-PBS pH 7.4, 0.1% glucose).40,000 cells/well were then dispensed in 96-well plates in cAMP buffer[1XD-PBS, 1% BSA, 0.1% Glucose, 0.75 mM 3-isobutyl-1methyl-xanthine(IBMX, Sigma)] and incubated either for antagonist competition assay: 1hour at 37° C. with various concentrations of compound [0.01 nM-10 μM]followed by 30 min incubation at 37° C. with 4 nM of NDP-α-MSH (Sigma)or for agonist assay: 1 hour at 37° C. with various concentrations ofcompound [0.01 nM-10 μM]. 10,000 cells were transferred in 384-wellplates, lysed and incubated with cAMP labeled with the dye d2 andanti-cAMP M-Antibody labeled with Cryptate following the manufacturer'sprotocol.

Reading of HTRF signal was performed on Artemis TR-FRET plate reader(Cosmo Bio).

Curve Fitting

All curve fitting was conducted using non-linear regression analysesfrom PRISM (version 4.0c, GraphPad Inc.) and the determination of Rmaxand EC50 or IC50 parameters were obtained from sigmoidal dose-responsephase (variable slope) equation.

Generation of WT-hMC4R Double Tagged Construct

A cDNA encoding a wild-type human MC4R with a 3 tandem copies ofHemaglutinine (HA) epitote sequence from UMR cDNA resource center wasmodified using known techniques in the art (e.g., PCR, cloning) to fusedin frame at the C-terminal a venus-Yellow Fluorescent Protein (YFP)cDNA.

The resultant cDNA was then subcloned in eukaryotic expression vector,e.g. pcDNA 3.1(+) (Invitrogen).

Generation of Double Tagged WT-hMC4R Stable Cell Line and Cell Culture

The double tagged WT-hMC4R was transfected in HEK293T cells withlipofectamine (Invitrogen) following the manufacturer's instructions andpermanently transfected clonal cell lines were selected by resistance tothe neomycin analog G418.

HEK293T stable cell line expressing wild-type human melanocortin 4receptor (WT-hMC4R) containing an N-terminal 3xHA epitope tag and anintracellular C-terminal venus-yellow fluorescent protein (v-YFP) weremaintained at 37° C. in humidified air containing 5% CO2 in Dulbecoo'smodified Eagle's medium (DMEM) supplemented with 10% fetal bovine serum(FBS), 100 U/ml penicillin/streptomycin (DMEM complete/10% FBS). Cellswere generally at 70%-80% confluence on the day of assay.

Other Embodiments

From the foregoing description, it will be apparent to one of ordinaryskill in the art that variations and modifications may be made to thediscovery described herein to adapt it to various usages and conditions.Such embodiments are also within the scope of the discovery.

What is claimed is:
 1. A compound of Formula IA:

wherein R¹ is 1) halogen, 2) C₁-C₆ alkyl, 3) C₃-C₇ cycloalkyl, 4) aryl,5) heteroaryl, 6) NHR⁴, 7) C(O)NHR⁴, 8) C(O)-aryl, 9) C(O)-heteroaryl,or 10) C(O) heterocyclyl, wherein the aryl and the heteroaryl areoptionally substituted with one or more R⁷ substituents; R² is 1) C₁-C₆alkyl-heterocyclyl, 2) C₁-C₆ alkyl-NR⁵R⁶, 3) C₃-C₆ alkenyl-heterocyclyl,4) C₃-C₆ alkenyl-NR⁵R⁶, 5) C₃-C₆ alkynyl-heterocyclyl, 6) C₃-C₆alkynyl-NR⁵R⁶, 7) aryl C₁-C₃ alkyl-heterocyclyl, or 8) C(O)NH C₂-C₆alkyl-heterocyclyl, wherein the heterocyclyl is optionally substitutedwith one or more C₁-C₆ alkyl substituents, or one or more halosubstituents, or one or more haloalkyl substituents; R³ is 1) NR⁸R⁹, 2)C(O)NR⁸R⁹, 3) C(═NH)NR⁸R⁹, 4) C(═NC₁-C₆ alkyl)NR⁸R⁹, 5) C(S)NR⁸R⁹, 6)CH₂NR⁸R⁹, or 7) C(O)heterocyclyl optionally substituted with a C₁-C₆alkyl substituent; R⁴ is 1) aryl, 2) heteroaryl, 3) C₁-C₆ alkyl-aryl, 4)C₁-C₆ alkyl-heteroaryl, 5) C₁-C₆ alkyl-NHC(O) C₁-C₆ alkyl, 6) C₁-C₆alkyl-O—C₁-C₆ alkyl, or 7) C₁-C₆ alkyl-heterocyclyl, wherein the aryl,the heteroaryl and the heterocyclyl are optionally substituted with oneor more R⁷ substituents; R⁵ and R⁶ are both or each independently, 1) H,2) C₁-C₆ alkyl, 3) C₁-C₆ alkyl-aryl, or 4) heterocyclyl; R⁷ is 1) CN, 2)halogen, 3) haloalkyl, 4) C₁-C₆ alkyl, 5) OC₁-C₆ alkyl, 6) O-aryl, 7)O—C₁-C₆alkyl-aryl, 8) C(O)OC₁-C₆ alkyl, 9) C(O) C₁-C₆ alkyl, 10) C(O)aryl, 11) C(O) heteroaryl, 12) C(O)NH C₁-C₆ alkyl, 13) NHC(O) C₁-C₆alkyl, 14) C(O)OH, 15) C(O)NH₂, 16) NO₂, 17) heterocyclyl, 18) C₁-C₆alkyl heterocyclyl, 19) heteroaryl, 20) aryl, 21) NH₂, 22) OH, 23)CH(OH) C₁-C₆ alkyl, 24) C(OH)(C₁-C₆ alkyl)₂, 25) C(NH₂)═NH, 26)C(NH₂)═N—OH, or 27) C(NH₂)═N—OC(O) C₁-C₆alkyl, wherein the heteroaryl isoptionally substituted with aryl, C₁-C₆ alkyl, haloalkyl, heteroaryl orCH₂-aryl-F; and R⁸ and R⁹ are both or each independently 1) C₃-C₇-alkyl,or 2) C₁-C₄-alkyl-C₃-C₆-cycloalkyl, or a pharmaceutically acceptablesalt thereof to allow the drug to penetrate the cell membrane; or aprodrug, or the compound is labeled with a detectable label or anaffinity tag thereof.
 2. The compound according to claim 1 having theformulae:


3. The compound according to claim 1, in which R¹ is selected from thegroup consisting of: aryl optionally substituted with one or more R⁷substituents, phenyl substituted with one R⁷ substituent, phenylsubstituted with two R⁷ substituents, phenyl substituted with three R⁷substituents, heteroaryl substituted with one R⁷ substituent, NH-arylsubstituted with one R⁷ substituent, C(O)NH-aryl substituted with one R⁷substituent, halogen, and C₁-C₆-alkyl.
 4. The compound according toclaim 1, in which R² is selected from the group consisting of: C₁-C₆alkyl-heterocyclyl, wherein the heterocyclyl is optionally substitutedwith one or more C₁-C₆ alkyl substituents, or one or more halosubstituents, or one or more haloalkyl substituents; C₃-C₆alkenyl-heterocyclyl, wherein the heterocyclyl is optionally substitutedwith one or more C₁-C₆ alkyl substituents, or one or more halosubstituents, or one or more haloalkyl substituents; C₃-C₆alkynyl-heterocyclyl, wherein the heterocyclyl is optionally substitutedwith one or more C₁-C₆ alkyl substituents, or one or more halosubstituents, or one or more haloalkyl substituents; arylalkyl-heterocyclyl, wherein the heterocyclyl is optionally substitutedwith one or more C₁-C₆ alkyl substituents, or one or more halosubstituents, or one or more haloalkyl substituents; and C(O)NH C₂-C₆alkynyl-heterocyclyl, wherein the heterocyclyl is optionally substitutedwith one or more C₁-C₆ alkyl substituents, or one or more halosubstituents, or one or more haloalkyl substituents.
 5. The compoundaccording to claim 1, in which R³ is selected from the group consistingof: C(O)NR⁸R⁹, C(═NH)NR⁸R⁹, C(═NMe)NR⁸R⁹, C(S)NR⁸R⁹, and CH₂NR⁸R⁹. 6.The compound according to claim 1, in which R⁴ is selected from thegroup consisting of: aryl substituted with one R⁷ substituent, arylsubstituted with one OC₁-C₆ alkyl substituent, aryl substituted with oneC(O)OC₁-C₆ alkyl substituent, aryl substituted with one C(O)NH₂substituent, and aryl substituted with one carboxylic acid substituent.7. The compound according to claim 1, in which R⁵ and R⁶ are as follows:R⁵ and R⁶ are both hydrogen; R⁵ is hydrogen and R⁶ is C₁-C₆ alkyl; R⁵ ishydrogen and R⁶ is C₁-C₆ alkyl-aryl; R⁵ and R⁶ are both C₁-C₆ alkyl; orR⁵ is heterocyclyl and R⁶ is C₁-C₆ alkyl.
 8. The compound according toclaim 1, in which R⁷ is 1) CN, 2) halogen, 3) C₁-C₆ alkyl, 4) OC₁-C₆alkyl, 5) C(O)OC₁-C₆ alkyl, 6) C(O) C₁-C₆ alkyl, 7) C(O) heteroaryl, 8)C(O)OH, 9) C(O)NH₂, 10) heterocyclyl, 11) heteroaryl, 12) C(OH) C₁-C₆alkyl, 13) C(NH₂)═NH, 14) C(NH₂)═N—OH, or 15) C(NH₂)═N—OC(O) C₁-C₆alkyl.9. The compound according to claim 1, in which R⁸ and R⁹ are as follows:both R⁸ and R⁹ are both C₁-C₆ alkyl; R⁸ and R⁹ are both C₁-C₄alkyl-C₃-C₆ cycloakyl; or R⁸ is C₃-C₆ alkyl and R⁹ is C₁-C₄ alkyl-C₃-C₆cycloakyl.
 10. A compound according to claim 1 or a pharmaceuticallyacceptable salt thereof, and selected from the group consisting of: CpdNo Structure 1

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11. A pharmaceutical composition comprising a compound according toclaim 1 and a pharmaceutically acceptable carrier.
 12. A compoundaccording to claim 1 or a pharmaceutically acceptable salt thereofhaving the structure of compound 142.